British Cruisers

1. This account is based on Notes on Naval Air Defence dated 2 January 1937, circulated by DNC Stanley V Goodall to his sections. Copies are in the Fiji Cover and also in the General Battleships Cover. This paper laid out various kinds of air attacks: high bombing, dive bombing, torpedo attack, and close-range attack (strafing) by day, and individual high-level bombing, dive bombing, and torpedo bombing by night. High-level bombers were expected to salvo their bombs (on command from the flight leader) from 10,000 to 14,000ft altitude, the maximum in a group being eighteen (typically divided into flights of three to five, flying at up to 200kts speed). By this time the Royal Navy certainly accepted that US-style dive bombing was feasible, since a dive-bombing attack was expected to begin with aircraft approaching at 10,000-15,000ft, diving in steps to 6,000ft, then making final dives at a 40–70° angle, releasing their bombs at 1,500–2,000ft at a speed of 200–300kts. Torpedo bombers would likely approach at 10,000ft in formations of no more than six, diving to attack at 6,000yds range (45° dive, maximum speed 200kts) and dropping their torpedoes at a height of 30-200ft and a range of 800-2,000yds, the maximum time between flattening out and dropping being five seconds. As in previous analysis, it was assumed that up to eighteen aircraft could crowd around one target (in this account, for simultaneous drops and successive attacks at thirty-second intervals). The maximum number of strafers attacking one target was set at six, at speeds of 150-250kts. The account of night attacks stressed how difficult it would be to illuminate the attacking aircraft, a theme carried over from previous evaluations of the air threat. Drawings in General Cover 1 show the expected ADO position in a Southampton. The ship had a pair of combined ADO and star shell sights at the after end of her bridge, separate from the compass platform forward of the DCT. ADO would stand at the port sight, his assistant (AADO) at the starboard one. ADO was responsible for distributing anti-aircraft fire. He and AADO were both lieutenants. A smaller cruiser, such as a Dido, would not have dedicated ADO sights, instead ADO and AADO would stand to either side of the chart table, which was alongside the ship’s 3m navigational rangefinder. At least in the large cruiser, each ADO sight was surrounded by communication devices which made it an ADP: links to the HADT and to the pompoms and machine guns, with a selector switch to the LADT. There was also a gyro compass repeater and a master cease-fire push. The 1937 report advocated a sight recently developed on board the cruiser Devonshire. Ideally they were paired, each pair covering a 60° sector from horizon to zenith; the maximum time on duty should have been an hour.

2. ADM 167/91, Memos for 1934. The key point raised in the Board memo was that the ships had been designed in view of war experience with light ships, on which basis their machinery was unprotected. Since then foreign navies had built large numbers of fast superdestroyers and, in effect, armoured cruisers. Memo dated 18 October 1934, describing the planned upgrade.

3. The surviving ‘E’ class Cover gives details. By 1942 Enterprise had had her No. 7 gun replaced by a pompom. When modernisation was ordered in September 1942 it included restoration of that gun and removal of the two after sets of torpedo tubes. She would be given new masts and new plotting arrangements in her bridge structure, as well as a new air-defence position, new radar and a new Type 132 Asdic. By this time Emerald had already had her two after sets of tubes removed, and she had two quadruple pompoms. In 1943 the allowance for both ships was seven 6in, three 4in HA, two quadruple pompom and six twin Oerlikons, one E.I.H catapult, and two quadruple torpedo tubes.

4. Controller (Rear Admiral Henderson) announced the programme, which he described as acceleration of fleet AA rearmament, in a memo dated 18 March 1936; the decision was reached at a meeting with CNS (i.e. First Sea Lord Admiral Backhouse). Additions and alterations need no longer await the need for large repairs. Some reserve anti-aircraft equipment had already been ordered to make up for deficiencies, under the 1935 programme. This memo and the list of planned upgrades are in General Cover 1. ADM 116/4037 gives policy statements concerning the programme. Progress was reported to the Board on a quarterly basis, the reports being included in Board Memoranda. The Defence Policy and Requirements Subcommittee (of the Committee on Imperial Defence) approved the Class II antiaircraft rearmament programme (as DPR.196) in July 1937 subject to Treasury sanction. Class II included producing or modifying guns to arm merchant ships.

5. The Class I programme kept changing. Thus the report of the 6th Meeting of the AA Rearmament Committee, in 1938, included the decision that a Board decision on the design for ‘C’ class rearmament was still pending, and that equipment for these ships would not be needed during the first half of the year. Approval was being sought to rearm Amphion (to become HMAS Perth) between December 1938 and April 1939 (Apollo had already been rearmed). HMS Achilles could not have her fire-control gear modified until she returned from New Zealand in 1940 (that did not happen), and an Australian decision on HMAS Sydney was pending. Emerald and Enterprise would not be rearmed until September and June 1940 respectively. Hawkins and Frobisher could not be taken in hand before 1 March 1939. No time would be saved by rearming them like Effingham without materially altering the ‘C’ class conversion programme, in which case fire-control gear, the limiting factor, would become available earlier.

6. As described in July 1937, the approved set comprised eight 4in guns, one HACS, two quadruple pompoms and two quadruple 0.5in machine guns. Approval was sought for eleven such sets for cruisers plus seven for merchant ships. When the merchant ship-conversions were discussed, ACNS proposed two rather than one HACS for them, but DNC provided only one, in view of a later production decision. DTSD pointed out that the two prototypes had two HACS each, and that a ship with so powerful a battery should be able to engage two targets simultaneously. The only exceptions were sloops with eight such guns, which clearly lacked space for the second system. DTSD accepted that some of the ships would be scrapped before the second control system became available.

8. A July 1937 paper refers to DNC’s sketch designs. An unusual feature of the design was that each mount was provided with multiple hand-ups from ammunition hoists terminating on the deck below, the mount being served by the nearest hand-up, depending on how it was trained.

9. The choice was either to replace two of the three 60kW steam (reciprocating) generators with two 200kW turbo-generators and adding motor-generators to convert DC to AC for the armament; or adding two 200kW diesel generators specifically for the armament and adding more generators to meet the increased DC load; or replacing one 60kW turbo-generator with a 200 to 250kW AC turbogenerator with a good overload rating, to supply armament directly and, through a motor-generator, DC power to the ring main, plus a second AC turbo-generator (200kW) for the armament alone. There was some question as to whether a 200kW diesel generator would fit within the ship’s deck height. The choice was to replace one of the 60kW generators with a 200kW AC unit and to install a new 200kW AC generator, with two 60kW motor-generators suitable for conversion from DC to AC or from AC to DC (electric motors are reversed electric generators).

10. Armament would have been four 5in/38 Mk 30 with two Mk 37 directors, two Oerlikons on the bridge wings (as in Curacoa), two 0.5in or Oerlikons aft, and two pompoms amidships as were being considered for ‘C’ class AA ships with two directors.

11. Dimensions: 546ft (wl) x 61ft 6in x 17ft 3in. Bessant Constructor’s Notebook 4. Unfortunately Bessant concentrated on the development of the Belfast class after making the estimates described. The Notebooks of the responsible senior constructor, Kennet, have not survived. W G John, whose Notebooks have survived, took over the 8,000-ton cruiser project in October 1936.

13. Lillicrap Constructor’s Notebook 6. Unfortunately Lillicrap was not assigned to develop the design alternatives for this ship, and no comparable Notebook has survived. ADM1/9402 contains the designs submitted, but not the reasoning behind them.

14. W G John Constructor’s Notebook 11 shows estimated displacement for K25G* of 8,210 tons, up from 8,150 tons a few weeks earlier. She would require about 74,000shp for the desired 31.75kts in standard condition, and deeply loaded would make 30.25kts; machinery weight was 1,440 tons, and armament weight was 1,050 tons. K31 was credited with 66,000shp (31kts at standard displacement, 29.6kts deep), the reduced weight of her machinery making up for her heavier 6in battery. Required endurance for both ships was 7,000nm at 16kts, six months out of dock. K31 particulars given to the towing tank (Haslar) in December 1936: 550ft (wl) 526ft (pp) x 59.5ft (wl) 60ft at upper deck x 16.5ft (depth 33ft on centreline, 32½ft at side).

15. The two designs are compared in W G John Constructor’s Notebook 11. Vickers offered eight twin 5.25in, the usual two multiple pompoms and two quadruple 0.5in machine guns, and two triple torpedo tubes. Protection would have included a 3in belt covering machinery and magazines, covered by a 2in deck. Dimensions were 540ft wl/535ft pp x 57/60ft upper deck x 52ft 6in depth mld x 16ft 6in mean. Machinery: 75,000shp (300 rpm) for 32kts. Vickers admitted that the ship was 700 tons heavy, and John estimated that she would actually displace 8,967 tons. His analysis was dated 13 October 1936.

17. The preferred four-shaft arrangement produced 66,000shp using four boilers (300rpm, 11ft propellers 1,180 tons). The alternative was a 72,000shp two-shaft arrangement using five boilers (240rpm, 15ft propellers, 1,435 tons). The five boilers would have been arranged in tandem, because otherwise the shafts would have had to be too far apart, so that they could clear the boilers.

18. According to a typed report dated 9 November 1936 (W G John Constructor’s Notebook 11), calculated metacentric height in standard condition was 2.08ft, compared to 3.27ft for a Southampton and 2.79ft for the Modified Leander. With a beam of 59ft 6in, the new ship would have a metacentric height of 2.09ft at 8,150 tons and 1.90ft at 8,300 tons. With 60ft it would be 2.34ft at 8,300 tons.

20. Sketch and data in W G John Constructor’s Notebook 11. Although not labelled as such, this was probably K32 (K33 was the Abdiel class fast minelayer). A very crude sketch showed the 4in magazine between the forward boiler room and the forward engine room, the machinery otherwise divided as in recent cruisers; the magazine of No. 3 turret would have been 61ft forward of the forward boiler room. Unusually (perhaps uniquely) the sketch was used to estimate the required length: a total of 95ft for the magazines etc under the three forward gun mounts (the forward end of this length coincided roughly with the barbette of No. 1 turret), a 34ft forward boiler room, 24ft for the 4in magazine, 41ft for the forward engine room, 52ft for the after boiler room (boilers in tandem), 48ft for the after engine room, 34ft for the magazine under No. 4 turret, with shell room above it. At the after end of the ship, 117ft was allowed from the after boiler room bulkhead to the rudder post (presumably indicating allowable propeller shaft length), and 24ft from the rudder post to the stern at the waterline. Waterline length seems to have been calculated on the basis that the centre of buoyancy had to be shifted to keep the ship on an even trim, rather than on the basis that dryness required that the forward turret be a particular distance from the bow.

21. W G John, who prepared the estimates for the new ship, was responsible for analysing Gorizia.

22. The US Navy suddenly decided to add underwater armour to the North Carolina class at about the same time, to deal with the same sort of threat.

23. According to W G John Constructor’s Notebook 11, Controller (Admiral Henderson) said that he had to think about this possibility, but that it should not be mentioned to E-in-C. Hearing about the exchange, DNC asked what would be the length of such a ship, and what reduction in armament would be necessary to bring it to 8,300 tons. Mr. John started with a 33.5kt ship and asked how much power he needed: as a first cut, 99,000shp, not far from the 96,250shp he got by boosting the 72,500shp of the new design by 30 per cent. He tried lengths of 550ft, 560ft and 570ft (waterline), and concluded that it did not pay to lengthen the ship. He could not approach E-in-C for possible machinery box dimensions, but noted that Yarrow was advocating a boiler which would actually reduce boiler room length by 6ft while increasing output. He estimated that he would have to save 340 tons in a 550ft ship or 387 tons in a 560ft ship. Simply reverting to twin 6in guns would save 321 tons, so the ship could retain her side and deck armour. More detailed calculations would show additional savings due to smaller magazines and shell rooms. The ship could have two triples and two twins if her belt armour were reduced from 3½in to 3½in and deck armour from 2in to 1¾in (but 2in could be retained over the 6in magazines). The torpedo tubes would be deleted. These steps would save 333 tons. The other 7 tons could come out of the 4in magazine crowns. Another possibility was to replace the two triple torpedo tubes with one quadruple (but it is not clear where it would have gone). John then developed a series of alternative schemes. Scheme X deleted all aircraft and torpedoes, while Scheme Y deleted the aircraft but retained one set of quadruple tubes, and had the deck shaved to 1¾in. Scheme Z left the torpedo tubes on board, but eliminated the aircraft and shaved deck armour to 1¾in (upper deck and magazine crowns). Then he tried more possibilities: deleting the torpedoes and taking another ¼in off the decks (Scheme R); reducing torpedoes to one quadruple mount and reducing decks and belt by ½in (Scheme S). By late April, Controller was discussing the idea with E-in-C. A lesser increase in power might be wanted; John estimated that the ship could make 32.5kts on 90,000shp, or 32.1kts on 80,000shp. John then developed five versions (A to E) of the 8,300-ton ship with 85,500shp (18 per cent increase) machinery sufficient for 32.5kts, differing in what was sacrificed. Scheme A sacrificed aircraft and torpedo tubes, but retained full protection. Scheme B sacrificed the aircraft and had 1½in decks over the machinery (but retained 2in over magazines). Scheme C retained the aircraft but sacrificed the torpedo tubes, and had 1¾in decks over magazines and 1¾in and 1½in over machinery. Belt armour was reduced from 3½in to 3½in. Scheme D had aircraft and torpedo tubes but 3in belt armour and the reduced decks of Scheme C. Finally Scheme E had the belt over the magazines increased to 3¼in, with a 1¾in deck over magazines and 1½in over machinery. W G John Constructor’s Notebook 11 includes a set of Legends dated 14 May 1937 for alternative designs A, A’, B, B’ and B2 with increased power. The A designs were the same length as the earlier design, 526ft pp, but the B designs were lengthened to 538ft pp. Beam was the 61ft 6in adopted for the 1937 cruiser, except that B2 was 61ft beam. Torpedo tubes were eliminated, except in B2. Displacements were about 8,200 tons. Power was boosted: to 83,000shp and to 86,000shp in A and B respectively, to 80,000shp in A1 and B1, and to 76,000 shp in B2, with various combinations of side and deck armour. Controller rejected the sacrifice in features such as protection associated with the 83,000 to 86,000shp power-plant, and asked instead for 80,000shp.

24. Either the boilers could be forced to give more power on roughly the original size, or squeezed down while giving 72,500shp at the higher forcing rate. E-in-C offered both alternatives in a memo dated 1 June 1937. The plant already accepted used a 180ft machinery box (1,280 tons). The new forcing rate was 61, compared to a previously-accepted 52. At the higher rate, a 72,500shp plant could give 84,000shp in a 182ft machinery box (1,430 tons). Alternatively, a 63,500shp plant could be forced to 72,500shp at the high rate (169ft machinery box, 1,250 tons).

26. Armament weight was reduced from 1,050 tons to 1,010 tons by omitting torpedo tubes, and armour weight was reduced from 1,340 tons to 1,330 tons. At this point B2 was credited with 76,000shp.

27. On October 1927 trials, the ship had a critical speed (about 24kts). At about this speed the wake shot out from the transom ‘like a needle spray bath’. When the ship accelerated from a lower speed this effect was seen at 23.8kts, and when power was reduced the effect disappeared at 24.1kts. Tank tests showed that the water shot out from below the transom to form a hump a little astern, leaving a vee of comparatively quiet water between the transom and the hump (i.e. in effect acting as though the stern were longer). A Haslar report of 5 July 1938 mentioned earlier model tests with a modified ‘C’ class hull (reported in June 1920) and with a modified Kent class hull (reported in September 1923).

28. The control position atop ‘X’ turret carried two officers (spotting and rate officers) and three ratings (two range takers, one telephone operator), plus a 22ft FM duplex rangefinder and spotting glasses for the officers. The DCT contained a 15ft FM7 rangefinder (ships were later fitted with 22ft rangefinders). It carried three officers (control officer, spotting officer and rate officer) and twelve ratings, including trainer and layer whose functions were duplicated by those controlling ‘X’ turret, a telephone operator, and two range takers. The DCT also had two ratings to operate its inclinometer (not duplicated in the ‘X’ turret position), a cross-levelling operator, and two wireless operators, plus two ratings at the PIL (Position in Line, for concentration firing) position. Two 9ft rangefinders on the compass platform supported the ship’s tactical plot (the DCT carried a shorter PIL rangefinder). Data from a summary of the ship’s fire-control system as of April 1938, in Fiji Cover 2.

29. Based on estimated performance of French and German shells exceeding that of British; it turned out that there was little or no evidence. DCNS said that the British were granting their enemies the best case and themselves the worst. Controller argued that a Fiji was well enough protected, and that a cruiser would rarely fight at the 90° inclination at which its armour seemed inadequate. The conference also compared Fiji protection with that of Southampton. DNC much preferred Fiji, particularly against air attack. At short ranges the belt might be penetrated, but the trajectory would be so flat that shells would pass over the magazines deep in the ship.

30. CAB 102/536, L Errington, ‘Naval New Construction Requirements September 1939 – December 1941,’ one of a series of unpublished Cabinet war histories prepared about 1946.

31. The deletions were relatively painless, but they did not completely cover the weight of the tubes and torpedoes: two 24ft boats (replaced by one 25ft boat of a new type), one after ladder, the sheet anchor and hawse pipe (already eliminated in 1938 and 1939 ships), side lining from all spaces other than cabins and officers’ living spaces, and the awning over the forward superstructure. DNC could find no further painless deletions, and ACNS demanded torpedoes as ‘of the greatest importance’.

32. The occasion was the dockyard conference prior to a refit. Addition of Types 284, 283 (three sets), 271 and two Type 282 had been arranged. What compensation should be arranged? The ship was scheduled for two Oerlikons on the quarterdeck, but the dockyard had insufficient labour to effect the approved compensation, stripping quarterdeck wood planking. Now two more Oerlikons (or 2pdr power singles) were wanted. After the conference, first priority went to radar (Types 284, 285 and 271). Next was close-in armament with splinter protection. The ship’s captain pointed out that removing two searchlights reduced the ship’s defence against night destroyer attack. Removing wood decking reduced habitability, which was worsened by the encroachment of RDF spaces. The ship already had four Oerlikons and two 0.5in, and the Captain wanted two more Oerlikons or, preferably, two single 2pdrs.

33. For a four-gun ship, these additions added up to 2,360ft-tons (weight multiplied by height above the keel), taking into account the effect on stability rather than just weight. The catapult and aircraft offered 1,220ft-tons. The centre gun and gear in ‘X’ or ‘B’ turret offered just 300ft-tons. Two Oerlikons on the quarterdeck cost 180ft-tons. Barrage directors for 6in guns cost 570ft-tons (equivalent to all three guns and gear of ‘Y’ turret or to five searchlights and their structures, at 110ft-tons each). Splinter protection for the HA armament was the largest potential addition, at 990ft-tons. Replacing pompom directors with predictors would cost 260ft-tons. Eliminating the port crane and lowering the boats would gain 930ft-tons. DGD’s proposals amounted to 1,250ft-tons, so dropping them would leave 170ft-tons to be found. That would equate to removing part of the main battery or aircraft or giving up the third searchlight.

34. The ship’s captain disliked Type 273 because it bore only out to Green and Red 115, and even so limited the training of ‘B’ turret under action conditions to 90° either side. Type 272M was approved as a replacement.

36. In 1937 Japan had not signed the treaty, but there was hope that she would do so, and it seemed (at least to the British) that Italy would soon sign (she did not). Thus Japan was the most likely builder, if Chile went ahead. DCNS doubted that the news that such a ship was being built for Chile would have much effect on the United States or the Soviet Union, but that it was being built in Japan would have enormous impact. He advocated bringing pressure on Chile. That did not work. Director of Plans thought the Chileans were interested mainly in quick delivery; the British could build faster than anyone else. They could offer two Fijis. Given the poor performance of the Italian-built ships in Argentine service, Director of Plans doubted the Chileans would buy Italian ships this time. The Chilean specification called for six 8in guns (maximum range 29,000yds), firing at up to two to five rounds per gun per minute, averaging one hit per minute on an 8,000-ton cruiser at 11,000yds. Other weapons desired were eight 4in, two quadruple pompoms, two 0.5in machine guns and two triple torpedo tubes. The ship should have a catapult and a double hangar with space for three aircraft. Desired speed was 31.5kts, with a range of 8,500nm at 16kts. Desired protection was a 4in belt (5in over magazines) with a 2in deck (3in over magazines); magazine immune zones against 6in and 8in fire were 7,000–24,500yds and 13,000–22,500yds respectively. DNC thought these figures feasible. The preferred Admiralty argument was that a Southampton or Fiji was better, achieving 1½ hits per minute at 11,000yds albeit not as well protected (immune zones for a Southampton were 8,000–20,000yds and 15,000–18,000yds). Unfortunately having 8in guns to face the Argentines’ 7.5in was probably more important than anything else. In October 1937 DNC cited Chilean protection requirements much closer to Fiji characteristics. Controller understood that builders in other countries had been allowed to bid whether or not construction itself was legal, and in February 1938 he suggested that Vickers and John Brown be allowed to bid with the understanding that they might not be permitted to build the ships. In February 1938 the Chilean attaché provided fresh details of what was wanted: 8,300 tons, six 8in (two triples), secondary AA armament, 30kts, heavy armour, triple torpedo tubes, three aircraft and a catapult, and radius of action 8,000nm at 14kts. These may have been the original figures, inspired by the characteristics of HMS Exeter and York.

38. British Naval Attaché, Santiago, 4 April 1939, in ADM 116/3921. He claimed that the ships were being built to Chilean specifications, using Yarrow boilers. Presumably they were the 8,700-ton cruisers De Zeven Provincien and Eendracht, which have always been described as replacements for the ageing Java and Sumatra.

39. W G John Constructor’s Notebook 12; reports from this exercise are also in the DNC Private Office papers in ADM 229.

40. She was 730ft x 86ft x 25ft, armament accounting for 2,990 tons and protection for 4,960 tons.

41. DNC told John to reduce belt and deck to 7in and 3in respectively (4in deck over magazines). In detailed calculations, bulkheads were 5in thick. Given the dimensions (700ft x 86ft x 22½ft) and a depth of 43.5ft, DNC wanted strength calculations leading to detailed hull weight. There was also a version of the 700-footer with a bulge, but with the same vertical belt as the others. Vertical rather than sloped belt armour was consistent with the recently-completed King George V battleship design, of which this was, in a way, a reduced-scale version. DNC’s detailed interest in the project suggests that it was more than a quick calculation to assess possible hostile programmes.

42. In detailed calculations, the barbettes of the 9.2in ship were given 10in sides but 9in ends.

43. The Japanese 20,000-tonner appears in notes in DNC’s private office files (ADM 229 series). The connection with Japan is also suggested by an adjacent page estimating armour weight for the new Japanese Tone class cruiser. The other design work in this Notebook, at this time, is concerned with weight growth and stability loss in the Fiji class.

44. This was the earliest in a list of ‘cruiser designs since 1939 developed by Section 7 [cruiser section]’ in a post-war Fiji class cover. Inclusion presumably means that it was developed in detail and was not merely a quick sketch ordered by DNC. In the list it is dated August 1939.

45. Both ships were given 580ft x 66ft hulls. Design A would have displaced 10,385 tons, Design B 10,030 tons. Most of the difference was machinery, 1,445 tons vs 1,120 tons.

46. A table dated 8 June 1939 showed resistance of various thicknesses of cemented (C) armour against 8in Mk VIII guns at different inclinations:

A 2in deck could not be penetrated inside 21,000yds, and could keep out a 250lb bomb from 5,000ft. A 3in deck would be effective out to at least 26,500yds, and it could keep out a 250lb bomb from 11,000ft and a 500lb bomb from 7,000ft. A 3½in deck would be required at maximum 8in range, 29,000yds. Required thicknesses were considered to be 6in belt and 2in deck. A note added in pencil stated that a German 11in shell could be kept out by a 2in deck at 23,000yds.

47. Drawings of this type are extremely rare in Constructors’ Notebooks, so these may indicate how seriously the project was being taken.

48. The next sketch design he did (dated 29 August) reflects the deepening emergency: it was for the 4.5in HA armament of a ‘Bank Line’ ship as an anti-aircraft escort. Armament would have amounted to four twin 4.5in, two quadruple pompoms, and two quadruple 0.5in machine guns, with a single HADT and its HACP John’s figures included 10 tons for radar (RDF).

49. The secondary armament, aircraft arrangements and endurance were all chosen by DNC. Speed was set at 33/32.5kts because the stated speed of the German ships was 32kts.

51. W G John Constructor’s Notebook 12 includes a horsepower calculation for a 33.5kt ship, 700ft x 56ft x 23½ft, 20,700 tons standard. The hull would have been bulged to 58ft below the waterline.

52. Turrets would have been protected more lightly. The 9.2in turret had a 6in face, 5in sides and 3½in roof; the 8in turret had 5in face and 2in sides and roof or, as an alternative, the same armour as the 9.2in. Presumably the 9.2in was the same gun being used for coast defence. As used in cruiser calculations, it fired a 410lb shell.

53. Comments signed by Rear Admiral T S V Philips, DCNS, 29 November 1939, in Heavy Cruiser Cover. According to a paper by Director of Plans, the 15in gun capital ship could be completed in spring 1944, an 8in cruiser in summer 1944, a new 14in or 16in capital ship in winter 1944 (if ordered at once), and a 9.2in cruiser not until early 1945. At this time characteristics of the new Japanese cruisers of the 1937 programme were unknown, but they were suspected of carrying guns of over 8in calibre, and of displacing 12,000 to 16,000 tons (none of which was correct). In view of the ‘characteristic Japanese lack of originality’, they were presumably based on German designs, and were probably up-armoured ‘pocket battleships’ displacing about 14,000 tons. It was also thought that the Japanese had sacrificed endurance for protection and firepower (actually they had sacrificed protection).

2. The barrage director was a simple eye-shooting device using a ring sight. It had two settings for convergence of fire, near (2,000yds) and far (4,000yds), range and time of flight being preset on the associated automatic barrage unit (ABU) in the ship’s main battery fire-control system. Normally the ABU would fire the weapons automatically, the director operator pointing the guns (via magslip transmission) at the aim point, leading the target using his ring sight. However, he could also fire manually, using a pistol. The ranging radar fed its data into the ABU. At least in the last version (Mk III) the Type 283 radar used beam-switching for a limited degree of blind pointing, and a second operator could point the guns on that basis. The Mk III handbook (BR 1527) is in NHB.

3. A chart dated 14 November 1940 showed the great variety of Type 284 configurations already in use. The small pre-DCT directors of the cruisers Devonshire, Shropshire and Sussex could not accommodate Type 284. Note that there were separate transmitting and receiving elements, presumably the 3 x II top and bottom in version 12A. Norfolk was not included in the table, although she was fitted with Type 284 in September 1941. Her sister-ship Dorsetshire was not fitted. At this time the arrays were coded according to how many units (blocks of one or two reflectors [I or II] except as noted) were mounted, e.g. 12B (London) had 3 x II across the top of the DCT, one single on each side, and 2 x II on the bottom. Fijis with 15ft rangefinders and Kent had 12B. Fijis with 22ft rangefinders had 12A (3 x II upper tier and 3 x II lower). Until she had the new mast, Kent had 3R + 4 F: 4 fishbones on top of the director and II plus I reflectors (not fishbones) on the face of the DCT in front of the rangefinder. Suffolk had 12F: two fishbone arrays, three wide and two high, side by side, one transmitting and one receiving. All others had reflector arrays: 11A in Southamptons and Belfasts (3 x II on top, I each side, and II and I below); Dido had eight (2 x II below, plus, two, atop the other on each side of the DCT); the Sydney and Arethusa classes and Ajax had seven (II plus I on the bottom of the DCT plus 2 x I stacked on each side); Leander, Orion, Neptune and Achilles had 5A(II plus I on the bottom tier, I each side); and York and Exeter had 5B (II plus I somewhat higher, I each side brought onto the face of the director). In fact at least Leander and Achilles had a New Zealand-developed surface-gunnery radar.

5. Signal Division (Admiralty), Radio Warfare (S.D. 1080/47), issued 1949, in RG 38 ONI library of foreign technical and related publications, NARA College Park. Date of issue was 29 August 1949; this was one of the post-war series of historical technical monographs. RU4 used a reflector-backed dipole spinning at up to 120rpm. RU4 was particularly valued for its ability to detect and track aircraft radars. The others in the series were RU1 (130 to 500 MHz), RU2 (500 to 1,000 MHz), and RU3 (1 to 3 GHz). As of August 1945, RU4 was expected to be in full production at the end of the year, along with RU1. The other two would follow. Cruisers and battleships were to have one RU1 and one RU4, plus lower-frequency sets.

6. Cdr J O H Gardner RN, ‘The Evolution of the Modern Gun Mounting: Pt III, The Remote Power Control of Guns’, in Papers on Engineering Subjects (predecessor to the Journal of Naval Engineering) (Sept. 1946) (copy in the Brass Foundry NCD series). Other sources were articles in the 1946 AGE Journal. Gardner pointed out that hydraulic drive (which the Royal Navy generally favoured) was lighter for a given power output, produced more torque (hence needed less power to accelerate its own mass), and could last much longer; electric drive was simpler, quieter, cleaner, and easier to produce (i.e., better adapted to mobilised civilian industry), and offered less fire risk. By 1946 British practice was to limit hydraulic RPC to heavy mountings which already used hydraulic power, and to use electric RPC for everything from 4in guns down. RP 10 and RP 40 both exerted control via hydraulics. In RP 10 a pump pushed fluid into a driving system; the magslip controlled the throttle on the pump to control the system. In RP 40 control was exerted by changing the amount of fluid running around a closed circuit by controlling the pump driving the fluid (the angle of a swash-plate pump was controlled by the magslip signals). RP 50 was all-electric using a metadyne which controlled the electric motors on the mounting. Metadyne control in particular required a considerable additional space (the metadyne had been developed by Metropolitan Vickers for the London Underground system). Magslip signals were electronically amplified to control two generators (training and elevation), each of which controlled a motor on the mounting. Estimated weight for a pompom installation (as calculated in 1940) was 2,600lbs below decks plus 1,100lbs on the mounting (or 3,400lbs plus 1,500lbs on a 4in mounting). Both RP 10 and RP 50 were applied to pompoms.

7. Even the boats on board cruisers could be inadequate. In 1942 the captain of a Fiji pointed out that nearly half the crew were typically granted shore leave after fourteen days at sea. Leave might be given for only four or five hours, but it took five trips to land 260 liberty-men. Once, when only 150 wanted liberty, all boats were not in service, and the last trip left the ship two hours after leave was piped. This would become a matter of grave concern if sailing orders were received towards expiration of leave. The boats themselves were unreliable, and the stowage left them at the mercy of 4in blast and buffeting from the sea.

10. On 30 July 1940 DNC asked that, as a first action concerning the Fijis, a rough estimate be prepared of the displacement and speed of a ship with Dido armament and protected by 60lb side, 2½in decks, and boxed magazines The belt would be reduced from 130/140lbs to 60lbs and extended from the after end of the citadel to the stern. The upper deck would be 2½in (100lbs) on a structural deck; the lower deck would be 2½in worked structurally, protection being extended aft in way of the lengthened belt. Magazines would be boxed (60lbs NC sides and 40lbs NC tops). More weight would have been added than removed, and removing machinery low in the ship could not compensate for adding weight high in the ship. Having done the calculations, W G John (Notebook 12, July 1940) suggested retaining the existing 2in armour on upper and lower decks, which would solve the stability problem. Having calculated that a ship with Dido armament and Fiji hull form could not have satisfactory stability with upper decks armoured throughout, John offered an alternative retaining Fiji side armour but gaining 2½in armour on the upper deck (the lower deck remained 2in), and with boxed magazines. It would be somewhat larger than a Fiji: 10,500 tons standard (595ft x 65ft x 17½ft [hull depth 32ft 3in], with a transom stern), making the same speed as Belfast (32.5kts) on 80,000shp.

11. As listed in September 1940, added protection was 30lb DKM plating on the ship’s side between platform and lower decks, over the magazines; ring bulkheads and trunks of turrets increased from 20lbs to 40lbs D plating; protection in way of steering gear brought out to the ship’s side to be continuous with DKM plating; additional splinter protection to cables, bridges, and way of pompoms, and over ready-use magazines; and plating on bulkheads at stations 83 and 99 (forward and after bulkheads to forward engine room) was increased to 40lbs (1in). In August 1942 DNC decided not to thicken analogous engine-room bulkheads in the Tiger and Minotaur classes because they had better deck protection.

12. Originally the gun was to have elevated only to 30°, but it was then re-thought as a dual-purpose weapon with a maximum elevation of 70°; it could then be used during the day. That entailed further changes: magazine stowage for ammunition and some form of fire control. The constructor involved commented that ‘it seems a pity in a ship mounting 8 5.25in HA guns to complicate things for one single 4in HA gun’. Controller decided that the gun would be limited to ready-use ammunition, but that did not solve the problem of additional complement – in a ship which had lost a bridge level forward.

13. ‘Y’ turret was considered too low to control the whole of the 6in battery, and the local director sight in it was not set up to direct other guns. In divided control, one group would consist of ‘Y’ turret only. That hardly justified the clock, with its wiring and changeover switches, in the transmitting station. DNO proposed to substitute a simplified Fire Control Box (used in sloops for anti-aircraft and surface fire) in ‘Y’ control position to allow control from the HA/LA director tower aft. The box would be able to transmit range and deflection to ‘A’ and ‘B’ turrets if the transmitting station were knocked out (e.g., by flooding), the entire armament being controlled from the HA/LA director tower through ‘Y’ turret operating in local control mode. There would not be provision in the ‘Y’ turret control position for spotting and rate officers, although the turret could be controlled from this position if all other control positions were out of action. The Fire Control Box would communicate its range and deflection data by emergency telephone.

14. Another argument favouring a squared-off upper bridge was that the jackstaff was not visible from the existing bridge. Those conning the ship used their view of the jackstaff as a way of seeing in exactly what direction the ship was steaming in relation to other ships. A squared-off bridge front was an alternative way to sensing the ship’s precise course. Abolition of the wheelhouse was controversial, as the quartermaster at the wheel could respond to general commands and thus reduce the load on captain and navigator. For example, he could be told ‘get that ship at 15° on port bow, and keep her there’. At a conference on 9 December 1940 on bridge design there was considerable interest in providing a protected fighting position on the bridge (the French had conning towers there).

15. All Fijis had been given plating on the fore bridges and cable trunks. The modified ships were given 20lb screens to their 4in guns, 20lb screens and deck to their pompoms, 15lb decks for machine guns, 15lb screens and deck for pompom directors, 20lb screens for torpedo tubes, 20lb for HACS supports, 15lb bulkheads and decks for RDF offices (Types 281, 282, 284 and 285), 15lb screen and deck for surface lookouts, 15lbs for the emergency conning position. The switchboard rooms moved from forward to an amidships sided position to reduce the length of vulnerable control cables. Circuit breaker rooms were staggered to make the ring main less vulnerable. The protective deck was extended forward and aft to provide a more gradual transition in the thickness of the strength deck.

16. George Moore, Building for Victory: The Warship Building Programmes of the Royal Navy 1939-1945 (World Ship Society, Gravesend: n.d.) describes the almost constantly-shifting Second World War programme. See also CAB 102/536. In February 1941 First Lord set the 1941/2 cruiser programme at three modified Fijis to be ordered at once plus four heavy cruisers to be ordered in the autumn (later deferred to March 1942 before the project died). Because the battleship Vanguard enjoyed special priority (at the behest of the Prime Minister), the cruiser Bellerophon, building at the same yard, was effectively suspended. For the 1942 programme the Naval Staff wanted seven modified Fijis, one in effect replacing the single 8in cruiser which had survived in the previous year’s programme. Controller agreed to six, but four were cancelled in August 1942 and another in November, Hawke being substituted. In December 1943 Minotaur and Superb were offered to Canada as a free gift. The offer was accepted on 7 February, but in April Superb was replaced by Uganda. The Canadians accepted the ships in a message in July 1944. No cruisers were included in the 1943 programme, but the 1944 programme included five of a new type.

17. In December 1941, Fiji was credited with a metacentric height (GM) of 1.5ft at light load and 3.4ft at deep load. Uganda was the same, because the weight and moment saved by removing ‘X’ turret had been exactly balanced off. The three ships ordered under the 1941 programme (63ft beam) were credited with 2.1ft light and 3.9ft deep. The ships just ordered would have a foot more beam (64ft): 2.6ft light, 4.5ft deep.

19. The DCT had to be able to turn 360° in either direction, presumably to follow fast surface targets; that required a longer and larger cable run below it.

20. Type 277Q should replace Type 277 (requiring a new mast) and Type 293Q should replace Type 293; Type 274 should be fitted with a stabilised aerial and with the Type 931 supplementary gunnery set. A standby warning radar (Type 268) should be fitted. An AEW receiver would be installed. The 1944 standard wireless and radio countermeasures outfits should be installed. A third gyro should be fitted (requiring yet more space). Spaces should all be air-conditioned to the latest standard.

22. As a very preliminary guess, DNC estimated that if the after machinery, after turret and all 4in guns were removed, space and weight might be available to install GAP and one or possibly two CR/MR mountings (the future twin 3in/70). If the after set of main machinery were retained, it seemed ‘very problematical’ that a GAP battery could replace the after turret and after 4in guns, ‘even assuming the most favourable developments’. The quadruple torpedo tubes would have to be surrendered. Removing the armament and after machinery would make possible conversion into a GAP experimental ship, but more investigation would be needed after requirements became firm.

1. For the earlier project, see the author’s British Destroyers (Seaforth Publishing, London: 2009). This one was dated 5 February 1940 in Lillicrap Constructor’s Notebook 7. It was a fast (35kt) low-freeboard ship with a protected hull and six bow torpedo tubes (eighteen torpedoes), gun armament being limited to one quadruple pompom. Lillicrap considered it actually a non-submersible submarine using ballast tanks to reduce buoyancy (hence silhouette) when attacked. Ballast tanks might also be needed for stability. It proved impossible to meet the desired characteristics on less than about 4,900 tons (the Legend weights totalled 4,965 tons) with dimensions of 400ft x 47 ft x 17ft, with 8ft freeboard (design development had begun at 3,500 tons). The machinery box would be 260ft long. With little space in the hull, much of the considerable accommodation needed for the large crew serving the machinery would have to be to submarine standards, in the superstructure above the protective deck. The ship would have a 2in curved (turtle) upper deck extending about 5ft below the waterline. Sides and top would be 30lbs for splinter protection. Initial estimates suggested that something like an Abdiel powerplant would suffice, but the sketch design submitted on 26 February 1940 showed a two-shaft 120,000shp plant. About 650 tons of oil would give an endurance of about 3,700nm at 12kts. The bluff submarine-like forward end would present particular problems at high speed. Details of design logic are in W G John Constructor’s Notebook 12. He went so far as to resurrect data on the Victorian torpedo ram Polyphemus (the First World War torpedo cruiser project was ‘New Polyphemus’). His sketch showed a submarine-like hull containing six 20,000hp boilers in four rooms (end rooms with one boiler each, two centre rooms each with two boilers in tandem), uptakes from each pair of boilers being trunked together into tall funnels. The funnels were connected by a flying deck, the fore end of which contained a splinter-proof conning tower. The after end of the hull resembled that of a submarine, and the cross-section was submarine-like.

2. Controller asked DNC for two alternative designs, armed with either four twin 4in or four twin 4.5in, on 29 February 1940. The designs are described in Tozer Constructor’s Notebook 1. They would also have two octuple pompoms. The initial 3in deck was soon changed to 3½in. Speed should be as high as possible. In the design developed, side armour followed the current practice of covering machinery to the upper deck (to protect boilers) and magazines fore and aft of that. Thickness was 1½inches. Approximate dimensions were 470ft (pp) 490ft (wl) x 54ft 6in. Displacement at 14ft 3in mean draft was 5,700 tons. This seems to have been the 4.5in version. Work continued as late as June 1940. Tozer Constructor’s Notebook 1 includes calculations for Design K, presumably with three twin 5.25in, displacing 6,380 tons (standard) and 7,850 tons deep. Design M had Abdiel class machinery, and Design N had ‘L’ class (destroyer) machinery. Endurance was calculated for 1,200 tons of oil at 16kts. Tozer Constructor’s Notebook 3 includes calculations for a follow-up, Fiji modified as an A/A ship, with four twin 5.25in, two octuple pompoms, and a thick deck. Provisionally the total depth of the new design would be 1.75ft greater than for a Dido. The ship would also have the usual pair of quadruple 0.5in machine guns and a pair of torpedo tubes. Legend details in the text are from a book of Legends maintained by DNC Department and held, at least at one time, in the National Maritime Museum; I am indebted to late David Lyon, at the time head of the Draught Room, for access during the 1970s, when I photographed it.

3. This entailed 40lbs over the ship’s side between upper and forecastle decks and blast screens on the forecastle deck; 40lbs over ammunition hoists (screens on the upper deck); protection to pom-pom ready-use magazine (60lb side, 20lb top, 40lb bottom, all NC); and 40lb tubes to the HACS supports.

4. Details in Harrington Constructor’s Notebook 4, dated 2 February 1940. The lists of weights added and removed do not include radar, a small weight but with considerable effect on stability. However, the same Notebook gives an extensive account of weights and moments for Type 281 a few pages later. The modified Belfast also occurs in W G John Constructor’s Notebook 12, with the note that beam is to be increased by 2ft 6in after a discussion with Lillicrap. On 19 December it was decided to add degaussing and also the D.IV.H catapult used in the Fiji class. A typed note in W G John Constructor’s Notebook 12 lists changes in the ships and notes that as inclined Belfast and Edinburgh displaced (presumably on average) 10,550 tons, hence the modified ship would displace 10,866 tons. GM in standard condition was expected to increase from 1.5 to 2.4ft, a measure of how well top-hamper was being reduced.

5. When he visited Bath on 8 January 1940, DNC agreed with Lillicrap that effective bulge protection would be impossible, hence that machinery and other spaces should be subdivided as much as possible, with boilers in separate boiler rooms and extra bulkheads in engine rooms. Lillicrap planned to try keeping boilers below the lower deck. Subdivision lengthened the citadel from 190ft to 250ft and also demanded a larger engineering crew. These considerations pushed the length of the 15,000-ton ship to 670ft.

7. W G John Constructor’s Notebook 12, memo dated 23 August 1940, referring to work completed while he was on leave (in a 6in cruiser file, now lost) and to further instructions. He began with a 580ft (wl) x 68ft x 17½ft (33½ft depth) ship, presumably the one recently sketched. The standard displacement given had been reduced by fifty rounds per 6in gun and by 100 rounds per 4in gun, from 10,950 tons.

8. W G John Constructor’s Notebook 13 includes a comparative table. The nine-gun ship (A) would have been 585ft (wl) x 70ft 6in; the twelve-gun (B), 615ft x 72ft 6in; Belfast was 606ft x 63ft 4in, displacing 10,540 tons. Both modified ships had 4½in belts (like Belfast) and 3in decks (2in in Belfast). Both had the six twin 4in guns of Belfast, but four quadruple pompoms instead of her two octuples. All three ships had 80,000shp powerplants. Speeds were 29.5/31kts (A), 29.25/30.75kts (B) and 31/32.5kts (Belfast). John also provided some higher-speed alternatives. To achieve 30.75kts deep, Design A had to be enlarged to 605ft x 72ft (12,270 tons) with 96,000shp. At standard displacement speed would be 32.25kts. Design B could have similar performance on 108,000shp (630ft x 74ft, 13,930 tons standard). In each case, the powerplant used four boilers. Alternatively, an eight-boiler plant like that of the earlier 9.2in cruiser studies could be used, but in that case a ship capable of 30.75kts at deep displacement would be even larger: 685ft x 85ft, 15,830 tons, 110,000shp. That was not too far from the 21,500-ton cruiser (720ft x 84ft) armed with nine 9.2in or twelve 8in guns, with an eight-boiler, 160,000shp powerplant offering a speed of 31.25/33.5kts. A comparative Legend dated September 1940 showed a modified Fiji with its 4in magazine abaft the after boiler room, and with the six twin 4in and four quadruple pompoms: 568ft (pp) 580ft (wl) x 70ft 6in, 11,280 tons, 89,000shp to make 31kts in standard condition. This ship would have Belfast side and deck armour (4½in and 2in).

9. A typed table in W G John Constructor’s Notebook 13 shows three sets of heavy cruiser data added 11 October 1940, the other data being dated October 1939 and 22 January 1940. The 10,500-tonner of 1939 used Fiji machinery (72,500shp with 80,000shp when forced). The January 1940 designs used higher power to achieve higher speed: 96,000shp for a 12,500-ton ship (610ft x 72ft) with thicker deck armour (3in and 2½in instead of 2in) and the same 5in belt as in 1939 or 125,000shp for a 15,300-ton (670ft x 77ft 6in) ship similarly protected with six rather than four twin 4in guns, and slightly faster (33/31.5kts). Two of the October 1940 designs reverted to the 5in/3in protection of the 1939 design, but had four quadruple pompoms instead of two octuple ones. Both had 80,000shp Belfast powerplants. The nine-gun version displaced 11,950 tons (590ft x 70ft), and was expected to make 30.75kts in standard condition. The eight-gun version displaced 12,300 tons (610ft x 72ft) and was expected to make 31kts in standard condition. A third design had 3in decks (2in plus 1½in plating) and nine 8in guns. That boosted armour and protection weight from 2,300 tons in the first October 1940 nine-gun design to 2,800 tons. The hull matched that of the eight-gun ship (610ft x 72ft), but displacement increased to 13,100 tons. It took 96,000shp to achieve 32kts in standard condition.

10. Design X was 10,300 tons (580ft x 66ft), with 90,000shp for 30.75/32.25kts. The nine-gun version was 9,245 tons (550ft x 64ft); the same powerplant would drive it at the same speed (reduced length balanced off reduced tonnage). Design Y was 14,050 tons (635ft x 75ft) with 100,000shp for 30.5/32kts. The nine-gun version of Design Y was 12,750 tons (605ft x 73ft) with 100,000shp for 30.75/32.25kts. Z was initially 625ft x 74ft x 19ft, 13,500 tons, which John thought he could cut down to 615ft x 75ft x 19ft, 13,200 tons. Unlike Belfast, Y had four twin 4in guns and four quadruple popmpoms rather than two octuple (X had two quadruples). All designs showed four rather than two quadruple 0.5in machine guns. All had the D.IV.H heavy catapult.

11. He also wanted the speed, in half-oil condition, of X, Y, and Z six months out of dock in the tropics: 29.5kts, 28.75kts and 29kts. Design Z was 13,500 tons (615ft [wl] x 78ft) and required 96,000shp.

12. The Admiral Graf Spee argument and the comparison with the improved 6in cruiser are from CAB102/536.

13. The Board seems to have become interested in 8in cruisers early in 1941, because W G John Constructor’s Notebook 13 includes three sets of estimates marked ‘work done at Admiralty, Whitehall, 13^th and 14th January 1941’ (p 61). The twelve-gun Design Z seems to have been used as a basis for a design with three twin 8in, one with three triples, and one with two triples. The ship with three triples was considered similar to Design Z: 635ft long (14,150 tons), 100,000shp (30.5/32kts), with 4in side and 2in and 3in decks. Raising the armour to the upper deck would increase displacement to 14,780 tons. The same change would increase Design Z displacement to 14,030 tons.

14. According to Moore, Building for Victory, p 144, the names initially chosen were Benbow, Blake, Effingham and Hawke, Benbow being changed to Albemarle and Effingham to Cornwallis by the new Ship Names Committee early in 1941. These names were approved by King George VI.

15. DNC ordered the first of these designs on 27 February 1941, according to a typed note in W G John Constructor’s Notebook 13 (p 71): nine 8in, 30.5kts deep, 12,000nm at 16kts; 4½in belt with 2in deck over machinery and 4in over magazines; close-range AA armament of six twin 4.5in guns, four quadruple pompoms, and Oerlikons; one heavy catapult and two aircraft (as in the Fijis). The forecastle deck would be the strength deck, carried right aft. The upper deck (i.e. the deck below the forecastle or weather deck) would be the armoured deck, except right aft. Gunhouse protection would be a 4½in face and 4in roof. A sketch of a 671ft (wl) x 79ft x 20ft ship shows one twin 4.5in gun alongside the bridge structure and two more alongside the superstructure between the two funnels, their magazine between the two machinery blocks. The sketch shows the superstructure deck (on which ‘B’ turret sits) extending aft to just forward of ‘X’ turret. Note that the belt is of constant height along its length, instead of rising to cover the forward boiler room. The version with four twin 4.5in eliminated one of the after pair on each side, but retained the pair near the bridge, presumably to reduce vulnerability. A drawing dated 7 March 1941 showed 637ft (pp) 651ft (wl) x 79ft x 20ft. Legends from the DNC Legend Book (Folio 18): see overleaf.

16. The Staff also wanted 1in bulkheads. Turret faces were to be 4½in, with 2in sides and roofs if possible. Protection generally followed that of the previously-designed heavy 6in cruiser.

18. The tentative Staff Requirement called for four heavy high-velocity automatic weapons of new design, possibly twins, of 50-60mm; and four medium automatic guns (Oerlikons or equivalent). The Staff also wanted two triple torpedo tubes and fifteen depth charges, the latter at that time standard on board British cruisers.

19. The design with four twin 4.5in (A or I) was 636ft (pp) 650ft (wl) x 80ft x 20ft 6in (freeboard 22ft 6in) (16,100 tons), with 110,000shp engines for 32.25/30.75kts. It originally had 150 rounds per 8in, but that was reduced to 100; and it had 200 rather than 400 rounds per 4.5in. Design II (sixteen 4in) was 656ft (pp) 670ft (wl) (16,500 tons); Design III (twelve 4in) was 643ft (pp) 657ft (wl) (16,200 tons); and Design IV (eight 4in) was 630ft (pp) 645ft (wl) (15,000 tons). All had the same 110,000shp engines, for speeds of 32.25/30.75kts, 32.25/30.75kts, and 32.5/31kts. Stowage for 4in ammunition was cut from 350 to 200 rounds per gun. A sketch of the 670-footer dated 23 March 1941 shows the forward 4in magazine ahead of the forward machinery block, separated from it by a generator (dynamo) room.

20. Discussions of the requirements are in ADM 1/12758, and, in shorter form, in the early papers of the Future Building Committee.

21. If the gun loaded at a fixed angle and then elevated to fire, bagged charges would suffice. DNO preferred them, as there would be no need to get rid of used cartridge cases, and more ammunition could be carried on a given weight. Loading at high angles added considerable complication and weight, so considerable weight could be saved by limiting the gun to 55° elevation. DNO wanted intermediate weapons (he was urging development of a 3½pdr) to reach aircraft at angles of sight over 50° flying at heights beyond the reach of 40mm guns. DNO pointed out that the existing twin 6in already elevated to 60°. For 1943 DNO could offer either the existing triple 6in modified to elevate to 60° or the existing 70° 5.25in mounting. The main modification envisaged was to allow for quick changeover between LA and HA shells: a two-bucket shell hoist would replace the existing endless chain. Larger ammunition capacity would also be needed. DNO provided weights of possible alternative armaments: three triple 6in, five twin 5.25in, five twin 6in (60°), four triple 6in and six 5.25in or twin 6in. Three triple 6in, as in a Tiger, weighed 420 tons, compared to 450 tons for five twin 5.25in.

22. The undated Legend for Design A is Folio 25 in the DNC Legend Book: 12,000 tons, 630ft (wl) x 70ft 6in x 17ft 6in (fwd) 19ft 6in (aft) standard and 23ft 0in deep; freeboard 31ft (fwd) 24ft 6in (amidships) 18ft (aft) at standard displacement. Armament was nine 6in (400 rounds per gun, far more than in existing ships), twelve Hazemeyer twin Bofors (twenty-four barrels), twelve twin Oerlikons, and two quadruple torpedo tubes, and the usual fifteen depth charges. Protection matched that of a Fiji: 3¾in side and 2in deck over machinery, 3½in and 2in deck over magazines, 2in turret roofs, 2in-1in turret sides. Power was 80,000shp (four shafts) for 31.75kts standard and 30.25kts deep; 3,750 tons of oil fuel gave an endurance of 6,000nm at 24kts when six months out of dock in the tropics (‘deep and dirty’). Weights: general equipment, 740 tons; machinery, 1,600 tons; armament, 1,250 tons; protection, 1,940 tons; hull, 6,230 tons; margin, 240 tons. The DNC Legend Book does not include legends for Designs B to L.

24. ADM 116/5150 for 1942-3 and ADM 116/5151 for 1944-5. Each volume contains both papers and minutes of meetings.

	Three twin 5.25in	Three triple 5.25in
Length	525ft	575ft
Oil Fuel	2,000 tons	2,500 tons
Speed	31.25–29.5kts	31.75–30kts
Endurance/20kts	6,000nm	6,000nm
Standard Displacement	6,800 tons	10,500 tons
Protect, RDF, etc as	Latest Dido	Latest Fiji

Formal Legends have not survived. Traces of some of the designs considered can be found in various Constructors’ Notebooks. Thus Gawden Notebook 1 includes tankage and armour weight calculations for Design G (four triple 5.25in guns, 71ft beam), October 1942 (dimensions were also given as 610ft x 69ft). Side armour would have matched that of a Fiji, with 3½in over magazines and 3¼ in over machinery; decks were 2in thick, and bulkheads 1in. An alternative Design J was 615ft x 69ft, with similar armour and armament. The design with three twin mounts was K; a modified K2 had two more Bofors and four more twin Oerlikons. The design with three triple 5.25in mounts (L) was worked out in November 1942; Gawden shows dimensions of 575ft x 68ft x 18ft 3in (hull depth 32ft).

26. A later meeting (on 30 November 1942) decided that there was too little difference between the 5.25in and the 6in to make a 6in cruiser of any type worth while. Given the probable difficulties of designing a 6in dual-purpose gun, ‘it was hardly worth pursuing the 6in type’. Later it was pointed out that 5.5in seemed to be the upper limit for a dual-purpose mounting, as anything larger would have to be fully powered.

27. A slightly later paper by DDNC(L) on the disadvantages of speed pointed out that three Didos had been torpedoed, Naiad and Hermione abreast the machinery spaces and Phoebe (twice) abreast the forward magazines, of which the first two had sunk after rapid flooding of machinery spaces. Two main machinery compartments of a Dido were 16 per cent of her buoyancy. There is no indication in this paper that DDNC(L) was aware of the flawed machinery arrangement.

28. Passmore Constructor’s Notebook 1 gives dimensions of Design M as 506ft x 55ft x 29ft x 15ft 6in; Design P had the same dimensions but 56ft beam. He gives Design N2 as 550ft (538ft pp) x 64ft x 32ft x 16ft 9in (8,650 tons). Design R was the much larger cruiser with 6in and 4.5 in guns. Legends of Designs M1, N1 and N2 were included in a presentation for the Board dated 30 June 1943, when N2 was being chosen as preferable alternative (Board Memos, ADM167/118). M1 was 520ft x 55ft x 29ft x 16ft 3in (7,150 tons); N1 was 550ft x 62ft x 32ft x 16ft 3in (8,200 tons), and N2 was as above. All were designed for 29kts at standard displacement and 28kts at deep load (not given). The 28kts at deep load was equivalent to 25.5kts deep load six months out of dock in the tropics. Power was, respectively, 44,000shp, 44,000shp and 48,000shp, in each case on four shafts. Endurance at 18kts when six months out of dock was 6,200nm, 6,000nm and 7,700nm, respectively. M1 had three and N1/N2 had four twin 5.25in (400 rounds per gun), each with its own HA director. The designs showed, respectively, six, six and eight Busters (twin Bofors) and eight, ten and twelve twin Oerlikons, plus, in each case, two quadruple torpedo tubes. In the N2 design, the Busters were forward and aft on the centreline, plus six sided, and at least half of the twin Oerlikons were hand-worked so that the ship could keep fighting if she lost power (this requirement may have been added when the associated Staff Requirement was written). All had 3in belts over machinery with 1in bulkheads, 1in (1½in for N2) magazine fore ends, and 1in shell room after ends. Decks were 2in (1½in in M1) over machinery and 2in over magazines. Turrets were ½in. Protection requirements: the belt over the machinery should defeat the ship’s 5.25in shells at 11,250yds (90° inclination) as well as German 5.9in shell (17,000yds) and Japanese 5.9in shell (12,500yds, 90° inclination). The deck over the belt should defeat 5.25in shells at all ranges, and German 5.9in inside 27,000yds (or Japanese 5.9in inside 22,500yds); it should also defeat a 500lb SAP bomb dropped from 2,500ft at an air speed of 300ft/sec (180kts). Magazines should be similarly protected, with splinter protection for turrets and steering gear.

29. The 44,000shp plant of N1 was replaced by a 48,000shp plant; endurance increased from 6,000 to 7,700nm at 18kts. Displacement increased from 8,200 to 8,600 tons. The modified ship could have eight rather than six Busters and twelve rather than ten twin Oerlikons. This N2 design was generally considered satisfactory. DGD would have liked the funnels closer still, but DNC retorted that a single hit should not take out both uptakes.

31. Minutes of the Future Building Committee meeting on 24 August 1944. It is not clear whether any designs had yet been prepared.

32. A table in the DNC Legend Book (Folio 31) lumps Designs Q and R together. Both designs showed eight 500kW generators, twice the equipment of a modified Fiji: four turbo-, four diesel-generators. Dimensions were 630ft(wl) x 74ft x 19ft 6in (fwd) 21ft 6in (aft) at standard displacement (14,200 tons); hull depth was 43ft. Power output was 100,000shp for a speed of 32.5kts standard and 31.5kts deep clean, equivalent to 29kts six months out of dock in the tropics. Endurance was 6,500nm at 20kts at full load under trial conditions, equivalent to 4,200nm at 20kts when six months out of dock in the tropics. Complement was 1,050, compared to 870 for Belfast, which displaced 11,700 tons standard as bulged and rearmed. Weights (Design R): general equipment, 780 tons; machinery, 1,900 tons; armament, 1,820 tons; protection, 2,200 tons; hull, 7,220 tons; margin, 280 tons.

34. The document refers to Japanese 5.9in shells, but Japanese cruisers had 5.5in guns. Bulkheads at the ends of the main belt were 100lbs NC, and 40lb DW bulkheads were fitted at both ends of the machinery units. Gun houses had 4in faces and 2in tops and sides, as in Belfast.

35. 655ft (wl) x 76ft x 20ft 11in, depth to upper deck 36ft. Standard displacement was 15,350 tons (18,708 tons deep, 17,283 tons in half-oil conditions); complement was 1,050 as a private ship. Armament weight was 2,049 tons. She would have carried 2,850 tons of oil fuel, for an endurance of 7,580nm at 20kts (reduced to 4,660nm when six months out of dock in the tropics). This ship met draft Staff Requirements dated 14 July 1944 (final ones were issued in August), which did not explicitly demand dual-purpose 6in guns. They called for 200 rounds per gun, but the figure 300 was pencilled in.

36. Displacement increased to 15,560 tons, beam to 76ft 3in, and draft increased from 21ft fore and aft to 21ft 3in fore and aft. The 250 rounds per 6in gun ammunition allowance was increased to 270.

37. There had already been some cancellations. This paper largely shaped the post-war British carrier fleet, in that it called for deferring construction of the four Gibraltar-class fleet carriers and also of four of the eight Hermes class (it did, however, call for continued work on all three Ark Royals, only two of which were built). By this time many lesser ships, including forty-two submarines, had already been cancelled.

39. Guns were 6ft apart, the minimum acceptable to prevent undue interference. The trunnions were 11ft above the roller path, nearly 4ft higher than in Mk 25, considerably increasing firing forces. A revolving cartridge holder at the gun held nine rounds, which could be fired in twenty-two seconds (twenty-six rounds per gun per minute), followed by a lull while the revolver was refilled. The gunhouse crew would number about fifteen. Protection at this stage was 4in face and 2in sides, roof, and back. Estimated revolving weight was 184 tons, more than a twin 8in (the constructor took 190 tons as a good estimate). The battery would be controlled by two LRS 1 (for divided control) and three MRS 1 controlling three turrets in separate controlled fire.

41. Rate of fire was ninety rounds per gun per minute. DNO estimated that each round would weigh 40lbs, and that the self-contained version would carry 600 rounds per gun. He expected it to weigh 25 tons, with a crew of sixteen.

43. Minotaur was not included in the 1944 Cruiser Cover, the comparison with Worcester being in the general post-war cruiser cover (without any lead-in showing the basis of the design). No separate Cover for this design has survived. The switch in designs, late in 1946, is evident in a volume of DNO notes for Controller (February 1947–November 1948) in Naval Historical Branch.

44. She was 645ft (wl) x 75ft x 20ft 9in (std) 24ft 0in (deep); hull depth was 44ft, and deep displacement was 18,415 tons. She was expected to make 31.5kts deep (clean) on 100,000shp with four shafts. Endurance ‘deep and clean’ was 6,000nm at 20kts. Design ZA was 13,070 tons standard (616ft x 73ft x 20ft/25ft 6in; 16,760 tons deep load). Because she was shorter, she needed more power to make the required 31.5kts: 110,000shp. Design ZB was 15,210 tons standard (616ft x 74ft x 20ft 3in/24ft 0in, 17,960 tons deep load) and would require 120,000shp. In comparable terms, Worcester displaced 15,210 tons standard (664ft x 70ft 7¾in x 21ft 6in/25ft 0in, hull depth 43ft 9in, deep displacement 18,000 tons). She was expected to make 32kts ‘deep and clean’ on her 120,000shp, or 32.5kts using the 10 per cent overload.

46. ADM 116/5966. The ten-year period was set by the Chiefs of Staff in a 1947 paper on future defence policy. They estimated five years in which war was unlikely and another five in which the probability of war would increase; after the ten years it would increase sharply. Thus 1956/7 became a horizon for force modernisation. The abortive building plan is in ADM 167/129, Board Minutes and Memoranda for 1947, as part of a lengthy long-range plan.

1. There were two arguments. One was that it would take until 1957 for the Soviets to make up for wartime devastation. The other was that Soviet nuclear development would set the timetable. By 1948 the British regarded the United States as the key to any war, so the Soviets would not fight until they had enough bombs (often estimated as 100) to disable the United States. The ‘year of maximum danger’ was a set interval after the Soviets exploded their first bomb, the date of which was estimated as 1952. The US government adopted the British approach and also the 1957 deadline (after plumping for 1955 for a time), but once the Soviets exploded their bomb in 1949, the US advanced the ‘year of maximum danger’ to 1954. The British did not, possibly partly because no earlier date was even remotely affordable.

2. This plan included a missile ship (not a cruiser) in its 1956/7 and 1959/60 programmes, and the modernisation of four cruisers: Royalist, Belfast, Swiftsure and Superb.

3. According to Paffett Constructor’s Notebook 2, p 183, about 20 June 1952 DTSD decided that the three missile ships formerly considered (A, 30kts; B, 20kts; and C, 12kts) should be fused into an 18-knot ocean convoy escort armed with one Sea Slug launcher and two twin 3in/70. This was the preface to a design study, using a merchant-ship hull.

4. The policies described here, including the decision for four cruisers and then for missile cruisers, are taken from the post-war draft Staff History held by the Naval Historical Branch and from my The Postwar Naval Revolution (Conway Maritime Press, London: 1986), the British programmatic sections of which were taken from Admiralty documents in the PRO. There is some question of interpretation, as it is not clear that references to guided-missile cruisers in the Staff History do not sometimes refer to all-gun large cruisers. The first major expression of the new deterrent-based strategy was the Global Strategy paper, a report dated 12 June 1952 by the Chiefs of Staff to the Defence Committee. The Chiefs of Staff reported on cuts after mobilisation in a paper dated 31 October 1952. Controller put the Navy’s case in 1954.

5. At a meeting in May 1952 DTSD said the Naval Staff strongly favoured torpedo armament, apparently to fire the new ‘Ferry’ guided anti-ship torpedo. The only available position was the quarterdeck, on which either four fixed tubes firing aft or one remote-controlled quadruple tube could be placed. Fixed tubes would save weight and did not have to be manned in action. However, there was no experience of firing torpedoes into or across a ship’s wake (and it was not clear how 6in blast would affect the tubes). To test the idea, two single tubes were to be taken from the frigate Relentless and mounted on board the trials cruiser Cumberland, one firing fore and aft and the other athwartships. About thirty to forty trial shots were required. The Ship Design Policy Committee decided to complete the ships without tubes, which could be installed afterwards if desired (the necessary trials went ahead). This option was never exercised. The star shell gun was dropped because it offered no other capability, although it did offer illumination (for target identification) at a greater range than the existing rocket flare. Presumably illumination was not very important in a ship optimised for anti-aircraft performance. However, the subject was considered important enough for fleet commanders to be polled. The rocket flare was their favourite.

6. MRS 3 used what the US Navy called a linear-rate computer. It projected ahead the observed rates at which the target was moving. Over time those rates changed, but the computer was not wired to calculate the change, so in effect the system was limited in range. LRS 1 presumably did not share this limitation. It saw no service as a gun fire-control system, but was the basis of the missile-control system used by the Sea Slug missile.

7. In 1948 MRS 3 was envisaged as control system for the new 3in/70 gun; as primary control system in destroyers which could not accommodate LRS 1 (to replace Mk VI director/Flyplane); and to control dual-purpose mountings split from primary control in new cruisers and destroyers. It would control 4in guns in AA frigates, and also 6in, 5.25in and 4.5in mountings when split from primary control in cruisers, carriers, battleships, destroyers and AA frigates. It required AC power (hence a motor-generator for power conversion in DC ships). Like other British (and US) fire-control systems, MRS 3 had a below-decks computer, space requirements for which could pose problems in older ships.

8. See the author’s British Destroyers and Frigates: The Second World War and After (Chatham Publishing, London: 2006).

9. Except for the two Tigers still being built in private yards, modernisation would be done at two Royal Dockyards (Portsmouth and Devonport), so nine years (to the 1957 target) gave eighteen yard-years of work. At this time only the ten Dido class had dual-purpose guns, so they enjoyed the highest priority for modernisation (they needed new fire controls). Worthwhile modernisation would take two years, and work on the Didos would leave eight yard-years for the 6in ships – for a total of four, plus the two Tigers in private yards. Priority for new construction was carriers and escorts, so it was unlikely that new cruisers would be built before 1957.

10. DNO was beginning to work on a new medium-calibre gun, at that time expected to be a 5in/70, which he hoped would become available in 1955. He expected the Mk 26 mount to be available for ship-fitting in 1952 if development proceeded at a normal rate, but spending on it had been cut in plans for the 1948/9 programme. The decision had been made to use US guns and ammunition, so that large supplies would be available in wartime, and it seemed that a proposal to incorporate the US 6in/47 into the existing twin mount design would take more time. All of these dates turned out to be delusion-ary; the 5in gun was abandoned in 1954, having formed the basis of a cruiser-destroyer concept. A meeting in November 1947 (chaired by Deputy Director of Naval Ordnance [DDNO]) decided that since modernisation was planned before 1955 (also a delusion), only the 6in should be considered. The projected fire-control systems were Flyplane, for 5.25in and 6in guns, and MRS III, for existing antiaircraft weapons and divided control of dual-purpose guns. Flyplane already existed, and could be provided 3½ years after a contract was placed. MRS III was expected to be available in 1954. The November meeting covered modernisation of the whole cruiser fleet. Flyplane was an anti-aircraft computer, so it was proposed in combination with an Admiralty Fire Control Clock for surface control.

11. A ship with three HACPs could take two Flyplanes, a ship with two HACPs (as in the original Fiji class) could take only one. In this sense the Improved Fijis with three turrets were equivalent to Tigers, but they could not take as much topweight.

12. There was no space in the machinery box for additional generators. Alternatives were one 1,000kW generator in space vacated by ‘B’ turret shell room, to serve both turrets; or one 500kW forward and one aft in place of the after 150kW diesel generator (finding space for a 50kW emergency diesel generator aft); or to replace both 150kW diesel generators with 500kW units. They could be steam or gas-turbine powered. This was one of the first British proposals for gas-turbine power. The two 500kW generators would not be connected to the ring main, but in the last proposal would also be emergency generators. In all cases the existing 500kW turbo-generators would be retained. However, to additional steam generators near the turrets would have long, hence vulnerable, steam lines. Another possibility was to replace the existing generators with more powerful ones. To further complicate the situation, the new weapons used AC rather than the usual DC power.

13. Key features were Type 274 radar, Type 932 radar (for splash-spotting), automatic cross-levelling (to compensate for roll), and improvement of the fire-control table (computer). All four requirements were met in Ceylon, Nigeria, Newcastle, Birmingham and Uganda (HMCS Quebec). Of the other ships, Superb and Swiftsure both had Type 932, as did HMCS Ontario. Automatic cross-levelling was on board Swiftsure, Kenya, Sheffield and Ontario. The computer improvement had been done in Kenya and Sheffield. The ships listed were those with the best surface fire-control systems, Nigeria otherwise being quite limited.

14. In 1950 Euryalus still had Type 79B, the first wartime air-search radar; Nigeria had Type 279, its immediate successor. The others had one version or another of the standard wartime Type 281. Most ships had Type 277 surface/air-search sets. Exceptions were the two New Zealand ships (Black Prince had a US SG1, and Bellona Type 268), Dido (Type 268), Sirius (Type 268), Diadem (Type 268), and Nigeria (SG1). Remarkably, Royalist had no surface search set at all, but she did have the Type 293 target-indication radar. Several ships, including Nigeria, lacked Type 293. Newfoundland and Superb were being fitted with Type 960 air-search radar; Swiftsure had Type 281BQ instead because of lack of time during a refit. Mauritius, Kenya, Jamaica, Gambia, Ceylon, Ontario and Uganda all had sufficient space and weight to take Type 960, and Bermuda was scheduled for installation.

15. See the author’s British Destroyers and Frigates: The Second World War and After for attempts to design or build a FADE.

16. These alternatives were listed in a sheet dated 14 November 1950, giving deep load displacements and metacentric heights for each. The original scheme with four twin 4.5in would involve an increase in complement of ninety men, hence was presumably not practicable. The ship would have displaced 11,670 tons deep (GM 4.22ft). All the other alternatives would have been possible without increasing complement. With two twin 4.5in, the ship would displace 11,548 tons (4.46ft, no trim); with six single 4.5in, 11,554 tons (4.56ft, trim 4in by bow); and with four twin 4in, 11,522 tons (4.57ft, 5.2in trim by bow). The emergency outfit included a barrage director and GDS 2*. Ratings required for the modernised battery, not including STAAGs, were 172, compared to 264 for the battery with four twin 4.5in guns. The problem was thus to eliminate ninety men. Note that the 6in Mk 26 battery required fifty-two ratings, the Mk 24 battery, ninety-two, reflecting the greater automation of the new mounting. A twin 4.5in mount required thirty men. Four MRS 3 Mod 1 required the same number (twenty-eight men) as four Mk 6M directors and their four FPS 5 computers below decks.

17. Modernisation, as planned in March 1953, would have added back the third twin 4in on each side, controlled by two MRS 3. The close-range battery would have been at least six Bofors Mk 11. Torpedo tubes would be landed. The ship would be fitted with TIU 3/Type 992 and the bridge enclosed. At this time plans called for replacing the 4in guns in Swiftsure and Superb with three twin 3in/70 (one on the centreline), and for installing the maximum possible number of L70 Bofors. Unfortunately the latter would have had to be converted to all-AC power, at an enormous cost. Detailed calculation showed that the goal of bringing 4in control up to Tiger standard in Belfast (with outstanding approved alterations and additions) entailed about 200 tons of overweight, which could be balanced by removing ‘X’ turret or multiple measures including deleting two of the twin 4in guns (keeping the original four) and eliminating the torpedo tubes. These measures offered only a total of 58 tons of compensation. Much more electrical power was needed. A revised Staff Requirement called for three triple 6in, four twin 4in (with two MRS 3) and six Bofors Mk 11. DTSD disliked the loss of the turret. DPT reception and a sixteen-track display were included and then dropped. In February 1954 plans called for retaining all four turrets plus four twin 4in, plus the six Bofors Mk 11s. The agreed Staff Requirement for what was now called limited modernisation (March 1954) showed eight twin L70 Bofors. It must have seemed ludicrous that DEE said that the modernisation would be as elaborate as that of Tiger (replacing TIU 3/992 with TIU 2/Type 293 radar helped). As of June 1954 it was estimated that the ship would displace 11,600 tons (light), compared with 11,800 tons before; and 14,716 tons deep compared with 14,826 tons, the current figures having been taken from a recent Inclining Experiment. They compared with 11,920 tons light in April 1945, 13,776 tons in average action condition (1954: 13,665 tons), and 14,933 tons deep load. A Legend dated January 1956 showed the four triple 6in turrets, six (rather than four) twin 4in (this may have been an error), and six twin L70 Bofors. Extreme beam was given as 67ft (a January 1955 Legend showed 69ft), and deep displacement as 14,895 tons. As of May 1956 the planned refits of Swiftsure and Superb had been scaled back to fitting new close-range weapons (six twin L70 Bofors) but also DPT, and possibly the new Type 965 radar (then called WAIR, which DND badly wanted). Like Belfast, both would have had closed bridges and lattice masts.

18. About August 1948 attack on, and defence of, trade became the second main task, the support of destroyer striking forces becoming the first of the secondary tasks. The June 1951 version of the Staff Requirement omitted trade attack and protection altogether, as well as reconnaissance (a secondary role in the earlier Staff Requirements). However, the central task of providing close air-defence was extended to include convoys as well as carrier task groups.

20. Both versions showed two STAAGs and six single Bofors, plus two quadruple torpedo tubes. The mixed-battery ship was expected to displace 9,551 tons standard and 11,705 tons fully loaded (deep). The all-3in ship would displace 9,191 tons standard and 11,345 tons at deep load. Estimated speed in deep condition (mixed-battery) was 31.5kts (31kts in the tropics); deep load speed was 30.75kts (30.26kts), the corresponding figures for six months out of dock were 29.75kts and 29.25kts. Speeds for the all-3in ship were given as 31.75/31.25kts standard, 30.9/30.4kts deep, and 29.9/29.4kts six months out of dock in deep condition. The average 3in ammunition load was 624 and 628 rounds per gun respectively.

21. Each 6in mount would have a Mk 6 director with Flyplane computer below decks, with one Admiralty Fire Control Table forward for LA fire, and one Admiralty Fire Control Clock aft for LA fire. If necessary, DGD would accept a fire control clock instead of the table, and dispense with the clock aft. Each 3in/70 would have an MRS 3 director. Gun direction would be by a TIU III with Type 992 radar (TIU 2/293 as interim if TIU III were not ready in time). If the 3in/70 was not ready in time, 4in guns could be mounted temporarily. Data from a note by DGD on 17 February 1948.

22. At a Staff meeting in September 1948 to discuss the Staff Requirement, Director of Plans regretted the limited armament offered, compared with large new Soviet destroyers which would have eight 5.9in guns, eight 3in guns and eight torpedo tubes (no such ships were actually built) and with the existing Kirov class cruisers (nine 7.1in and eight 3.9in guns). DGD pointed out that rate of fire and accuracy were more important than numbers of guns ‘and there was reason to suppose that the Tigers would be superior to their possible adversaries’. DTSD (chairman) pointed to the ships’ anti-aircraft role. Director of Plans ‘did not feel reassured’ in view of the vulnerability of only two gun mounts and the question of reliability; a single breakdown or hit would halve the ship’s main battery. The constructor responsible for the cruiser section (H S Pengelly) soon commented to DNC that with the planned armament the limit imposed by the relatively small hull had been reached, and even exceeded. Even if space could be found for a third Mk 26 in place of the forward 3in/70, it would add about 200 tons and would reduce stability unacceptably. If the new high-performance gun was essential for the primary role of the ship – anti-aircraft defence – then the reduction in number of guns and mounts could not be avoided. VCNS reaffirmed this conclusion. The two-turret arrangement did prompt DGD to demand somewhat thicker turret armour. Mk 26 had been conceived for the five-turret Minotaur; losing one turret was not nearly so serious as losing one of two turrets. Minotaur thicknesses were: 3in (originally 4in) face, 2in sides, 1½in roof, 1½in rear and 1in floor. Thicknesses proposed for Tiger were reduced: 2in face, 1½in sides, and 1in roof, rear and floor. Late in 1948 DGD demanded Minotaur thicknesses (with a 2in protective ring). The extra inch on the face was described as weight to balance the mount. DNC had pressed for minimum weight (splinter protection only), both for stability and to make it easier to train the turret at maximum speed.

23. In September 1948, estimated action load was 2,000kW, so the desired total generator capacity, exclusive of emergency diesel power, should be 4,000kW (with 3,000kW considered acceptable). There was a ‘reasonable chance’ that the four 500kW turbo-generators in the machinery spaces could be upgraded to 750kW, to give a total of 3,000kW rather than 2,000kW (this was DEE’s initial AC power plan). It would probably be necessary to upgrade diesel generator power to 700kW (say, two 350kW), which was impracticable. However, the 150kW diesel generator aft could probably be upgraded to 200kW. DEE stated that switching to AC would not involve extra weight, but it was not at all clear that a 3,000kW AC installation would be no heavier than the existing 2,000kW DC one. Conversion to AC power was likely to be expensive, although in the end an AC system would be more efficient and more suitable. DEE later proposed installing, if possible, two 1,000kW AC generators in place of two of the 750kW units, to provide a more nearly adequate reserve of electric power. By November, E-in-C wanted all four generators in the machinery space to be 1,000kW (DNC commented that when they went from 350 to 500kW they were told it would be very difficult). By this time all machinery, including the original quartet of 500kW DC generators, had been installed, but E-in-C pointed out that no doubt the generators could be used elsewhere. DEE claimed that the change to AC would save 75 tons (DNC’s cruiser designer, Pengelly, did not believe that). The estimated weight saving was later reduced to 65 tons, which could be set against an anticipated 100 tons excess (over Legend figures) in the DC design. DEE also pointed out that existing DC switch gear could not handle the loads now envisaged. At its sixth meeting (12 November 1948) the Ship Design Policy Committee decided that these and all future ships should have AC power, but given the implications of the decision, it wanted approval from First Lord and First Sea Lord. In fact First Lord was not informed when the order was given (March 1949) to cease work on DC drawings in favour of AC, on the theory that he would not want to be informed prior to consideration by the full board. Then that decision was reversed. The same meeting affirmed the Tiger design with Mk 26 and 3in/70 guns. The larger implication for cruiser modernisation was that DEE would want any cruiser rearmed with Mk 26 turrets to be rewired for AC, at a considerable price. The formal decision in favour of AC power was delayed because its cost was difficult to calculate, yet the increased expenditure required Board and Treasury approval. The change was probably set by January 1949. In March 1949 DNC estimated costs for the Treasury. The total cost of the planned DC installation was £1.6 million, of which £480,000 had already been spent. The AC installation would cost £1.4 million. Stripping out the existing installation would cost £40,000, and modifying machinery would cost another £80,000, but £200,000 of the DC machinery cost could be recovered. The net increase was £200,000, a seventh of the cost of the AC installation alone.

24. After the Board approved CDS for cruisers, approval was sought to buy a prototype for installation on board Superb; as of 1954 the requirements for CDS/DPT were being referred to the Air Defence Working Party for review in light of the new strategic concept of deterrence.

25. There were also delays in supplying key equipment. In July 1951 delays in providing the GDS 3 gun direction system would delay the ships by five to seven months, pushing expected completion dates to January 1956 (Tiger), May 1956 (Blake) and July 1956 (Defence). This was before the one-year deferrment.

26. These guns appear in the July 1953 version of the Staff Requirement, to be controlled by MRS 8, ultimately to be replaced by MRS 3 Mod 2. The L70 weapon was intended to replace the wartime L60 (i.e. 40mm/60). It offered greater effective range. For a time, the L70 featured in all new British warship designs, but it was superseded by the Seacat missile before entering service (the British Army did buy the L70).

27. Enclosures to the Ship Design Policy Committee dated 31 December 1948 from DNC (C S Lillicrap). The papers involved were ‘The Functions and Status of the Cruiser’ (SDPC(48)24), ‘The Shape of the Cruiser of the Future’ (SDPC (48)33), and ‘Protection of Convoys by Cruisers’ (SDPC(48)33). They appear to have been written by DTSD. He proposed visionary developments (for 1948) such as atomic power and flush decks with armament sunk into them (to deal with nuclear fallout and blast), but DNC chose to limit himself to developments already under way. DNC’s drawings are in the General Post-war Cruisers Cover.

28. Sketch I was 14,500 tons standard/17,500 tons deep (645ft x 74ft x 23ft deep). Sketch II would carry forty-eight missiles on 14,000 tons standard/17,000 tons deep (530ft x 73ft). The missile launcher and stowage displaced the two after twin 6in and also the two after twin 3in. A structure forward of the twin launcher carried a missile-assembly space, and had the Sea Slug director on top. The missiles themselves were shown stowed horizontally below the waterline in two compartments with a checkout compartment between them. Sketch II can be compared to the abortive 1956 missile cruiser, which had a similar main battery. Sketch III was 10,500 tons standard/13,000 tons deep (585ft x 68ft x 22ft). The drawing showed a Daring-style forefunnel with the lattice foremast wrapped around it, and a conventional after funnel, widely separated from it. Sketch I/II had the single funnel. Sketch IV was 12,250 tons/14,750 tons (600ft x 70ft x 23ft), with separate engine and boiler rooms forward and aft, separated by the 3in magazine amidships. It was expected to make 30kts on 90,000shp (four shafts) when ‘deep and clean’. This design showed fixed quadruple torpedo tubes in the raised area amidships. Funnels were as in Sketch III rather than the single funnel of Sketches I and II. Sketch V was a version of IV with two combined engine and boiler rooms forward but with separate boiler and engine rooms aft. It had three rather than four shafts. It would displace 12,000 tons standard/14,250 tons deep (580ft [wl] x 70ft x 23ft; 90,000shp would give 31kts in deep clean condition).

1. Paffett Constructor’s Notebook 2, which begins with a reference dated 28 March 1951 to Perry’s Sketch Design I. Unfortunately, Perry’s last Notebook in the Brass Foundry collection ends in 1946 (Paffett refers to Perry’s Book 11, which has not apparently survived). Paffett refers directly to the ‘Large Cruiser of 1960 – Sketch I’, so presumably that is the Perry design in question. His drawing of armour distribution showed a box over the forward magazines, and conventional belt and deck protection (with a high part to cover boilers) abaft that. The belt is 130lb (3¼in) NC, but the 60ft long box forward has only 60lb (1½in) NC on its side. End bulkheads are 130lb NC. Decks are 60lb (12lb structural, the rest protection).

2. In January 1952 the DACR (direct action close range) weapon was code-named Zenith. There were four possibilities: D.10 (30 tons), Scarecrow (39 tons), V.A. Crow T. (36 tons), and Marquardt (27 tons), each of which included 11¾ tons of ammunition.

3. Paffett wrote that he decided to try a 6in design because the virtues of the two heavy guns were still being debated. However, he also referred to TSD 00105/51, the preliminary Staff Requirement (which has apparently been lost). Hull weights were scaled from those of Belfast, corrected for the flush deck planned for the new ship.

4. Estimated weights for the weapons in contention, as of June 1951, were 225 tons for the twin 5in, and 280.5 tons for the twin 6in, 99.8 tons for the 3in/70, and 30 tons for the close-range weapon. In each case, weight included ammunition. Type 984 radar was expected to weigh 60 tons.

5. Paffett worked out armour for a 625ft ship (2,095 tons available): 3in side and 2in deck over the whole citadel. That was actually very tight, and he had to shave to provide it (he managed to increase armour weight to 2,250 tons by cutting endurance to 5,820nm at 20kts, or 4,580nm ‘deep and dirty’).

6. Paffett’s comments on CR 6 suggest that 3in guns would have to be on the centreline, because otherwise the ship could not make full use of these weapons. In that case CR 8 would have four centreline positions, compared to no more than five (two 3in, three 6in) for CR 4, since in CR 4 two of the 3in would be sided, as in Tiger. CR 8 length was given as CR 4 less a 6in, plus a 3in, which might equate to 625ft or 600ft, which was very long for an 11,000-ton ship. A estimate in November 1951 gave dimensions as 600ft x 65ft, with endurance 4,500nm ‘deep and dirty’ at 20kts, capable of 34.25kts ‘deep and clean’. On this basis, adding up known weights (hull, equipment, machinery, armament, fuel oil, reserve feed water and a 200-ton Board margin), only 300 tons was left for protection. To get minimal protection, Paffett proposed going to 12,000 tons, in which case speed would drop to 33.6kts ‘deep and clean’.

7. Some of the missing numbers represented alternatives not worked out in detail. CR 9 was a version of CR 8 with three twin 5in instead of two twin 6in and two twin 3in. CR 11 was a version of CR 10 with three twin 5in instead of the 6in/3in battery. CR13 was a version of CR 12 with three twin 5in. All of these ships had two quadruple torpedo tubes. CR 16 was Minotaur brought up to date (Paffett’s Notebook gives no details at all).

8. W G John Constructor’s Notebook 15 mentions a revised version of this TSD 2230/52 dated 8 August 1952 in a memo of 16 January 1953 describing the current study (22), a 435ft, 4,770-ton ship armed with two twin 5in and two twin L70 Bofors, with six-channel GDS 3 (Type 992 radar) plus air-warning and fighter-control radar (Types 982 and 983). The ship also had a single ‘stripped’ 4.5in star shell gun, six fixed torpedo tubes on each beam, single Limbo ASW mortar, and the Camrose anti-torpedo torpedo. On 30 July 1952 DNC had directed designers to use destroyer practice throughout. The memo proposed a 4,750-ton ship with endurance reduced from the desired 3,500nm at 22.5kts to 3,050nm. Note that at this point the twin 5in mounting was expected to weigh 270 tons.

9. Armament was four twin 5in, four Bofors Mk 12, and eight torpedo tubes. The ship would have a single Limbo ASW mortar, in effect left over from her rather distant cruiser-destroyer ancestry. John’s Notebook also shows a May 1953 study of a 15,400-ton cruiser armed with two twin 6in, four twin 3in, and four twin Bofors Mk 11, a slightly lighter battery. This ship would have been 650ft long.

11. W G John Constructor’s Notebook, 25 June 1953; John was also asked for a fast escort, on which he had been working.

12. T J O’Neill Constructor’s Notebook 1, as he resumed work on the CR series. This note was dated 11 November 1954.

13. These tables are in W G John Constructor’s Notebook 15, and surrounding documents suggest they were produced early in July 1953, about the time when the cruiser-destroyer was abandoned. The Notebook includes more detailed sheets describing the ships further. The big cruisers and the missile ship all had four-unit machinery. The 18,200-ton and 16,850-ton ships both had 2½in side and 1½in deck armour; radars were Types 960, 982, 983, 974 and 992. Both had four twin Bofors L70 as close-in armament. The 18,200-ton ship had twelve MRS 3 fire-control systems, the 16,850-tonner (and the 16,000-tonner), ten. The 13,000-tonner had three-unit machinery, hence its reduced speed (it also had eight rather than ten MRS 3 systems). All the new-design cruisers had two quadruple torpedo tubes. None of the cruisers had Type 984 radar. The 8,000-tonner was 550ft x 57ft 6in x 16ft (hull depth 34ft 6in). The Y102 powerplant offered a speed of 30.5kts ‘deep and clean’ (29.5kts ‘deep and dirty’) and an endurance of 3,600nm at 20kts. Armament was three twin 5in with MRS 3 Mod 1 directors, one sextuple Bofors (one MRS 3 Mod 2), two 40mm twin with TOM, GDS 3, and four triple torpedo tubes. It had 1½in sides and 2in crowns for magazines, and 2.5in sides and 1in deck over machinery. The ship had accommodation for 675.

14. This time the Type 984 aerial and office were taken as 35 tons, and the CDS system as another 30; GDS and Type 992 added 32 tons.

15. T J O’Neill Constructor’s Notebook 2, confusingly dated prior to Notebook 1, but devoted to missile ships. This entry is dated 6 September 1954 (O’Neill’s work on gun cruisers was dated November 1954).

16. This version showed four tandem bays, each with six missiles on three levels. Each level fed into a lift and traverser feeding missiles into two checkout spaces abreast the loaders which would place them on the twin launcher. Missiles failing checkout would be stowed in these spaces.

18. Associated equipment space would be about 3,000ft² (about 1,500ft² beyond what was already available), and the extra ten officers and sixty ratings would add another 3,000ft². Given a waterplane coefficient (0.82), the designer could estimate the effect of adding 20ft of ship length: 1,100ft² on each of three decks, a total of 3,300ft² – about half of what was needed. Three bridge decks, 20ft x 50ft each, offered another 3,000ft², which would be enough. The result was 550ft (pp) x 70ft x 18¼ft (hull depth 45ft), 11,300 tons.

19. GW 43 had two 6in guns but no 3in/70; she also had four twin Bofors. She would have made 32/31kts on 14,000 tons. This design seems not to have been worked out in any great detail.

20. In deep stowage, as used in the test ship Girdle Ness, missiles were stowed one atop the other in cradles. When needed, they were grabbed one by one by a crane overhead, moved to an opening in a watertight bulkhead, and rammed through. By way of contrast, tube stowage entailed continuous positive control of the missile, which was easy to move fore and aft using lugs to hold it to the stowage rails. Its railed supports had to move sideways (traversing) to move it off the fore-and-aft direction, but that was not too difficult to arrange. Sea Slug was also relatively easy to fin before launching; the need to stow it fully-assembled complicated stowage system design. The capacity of later ‘County’ class missile destroyers was greatly increased, nearly to that planned for the missile cruisers, by stowing some missiles partly assembled and assuming they would not be fired with the assembled ones. DNC disliked the considerable open volume of deep-stowage magazines and pointed out that they could not be vented satisfactorily. However, their worst feature was surely that the missile on its grab was not under full control unless a very complicated rigid grab was used.

22. ADM 1/27685, nominally on the role of helicopter ships in the ‘88 Plan’ (29 March 1960).

23. At this time frigates and missile destroyers typically deployed small helicopters without dipping sonars, hence essentially extensions of the ship’s own sonar system. The big ‘single package’ helicopters were limited to otherwise fixed-wing aircraft carriers to, according to D of P, ‘their mutual embarrassment and the detriment of the carrier’s main role’.

24. Detailed calculations are in Chilcott Constructor’s Notebook 1, 9 February 1961. These are mainly deck area calculations, hence do not provide much insight into design characteristics. Millman Constructor’s Notebook 17 includes a space analysis for Study 21H3. Stickings Constructor’s Notebook 2 includes capacity calculations for 21M15 and for 21N6.

25. A paper on the 1963 Long Term Costings in the Tiger Cover makes the interesting point that the 50,000-ton carrier then planned was only large enough to carry thirty strike aircraft, four airborne early-warning aircraft, and two search-and-rescue helicopters; adding ASW aircraft would push up the size and cost of the ship. It already seemed that displacement would go to 52,000 tons to accommodate two ASW Chinooks. On 54,000 tons, the most that could be driven by the planned three-shaft powerplant, two more Chinooks could be accommodated. To the extent that the carrier was cancelled because it was so expensive, conceivably greater reliance on the escort cruiser concept could have saved the project.

26. According to a history of the escort cruiser dated 6 September 1963 in the third Tiger Cover, no fewer than three formal proposals had come from the fleet over the past eight months: to convert Belfast to carry helicopters, to convert the Tigers, and to convert the LST Lofoten ‘as an interim off-shore garage’ until the FOST support ship (Engadine) was completed in six Wessex, with limited maintenance for eight days. Speed was 15kts, and endurance was 5,000nm at 15kts. Were it to be turned into a fleet unit, it would need both better maintenance facilities and better communications. The ship was unarmed and lacked command-and-control facilities. The one FOST ship in the programme was due to complete at the end of 1965.

27. This was Scheme Z, offering flight deck space for two Wessex (with rotors spread) and hangar stowage for four, with forty-eight Mk 44 torpedoes for the helicopters. Scheme X offered deck space for one Wessex and a hangar for three, and Scheme Y offered deck space for two and stowage for four, both waist 3in/70 mounts being landed. In Scheme Z the helicopters were stowed under the flight deck, hence the guns could be retained. Ultimately a form of Scheme Y (hangar forward of the flight deck) was adopted in which the flight deck was sponsoned out over the stern and the guns retained; the complication of a hangar under the deck (hence a lift) was eliminated.

28. An undated Legend of Blake as converted to operate Sea Kings showed a Seacat system (forty-two missiles) and two twin 3in/70. Standard displacement was given as 11,280 tons (full load 12,190 tons). As inclined upon completing conversion, Blake displaced 12,440 tons deep; 11,510 tons in average action condition; and 9,920 tons light.

30. In theory the four last ‘County’ class missile destroyers could trade armament for command and control spaces, but they were due to be discarded in the 1980s, when the command cruiser would reach mid-life. Once they were gone, that capability would have to go somewhere else. Accommodating the facilities in Type 42s would be difficult (a 1969 paper gave a price but then argued that it would be uneconomical to split up the limited number of Type 42s, and that in any case the desired level of command and control could not be accommodated in so small a hull.

31. As explained in an 11 December 1968 paper written to help support the Staff Requirement the following year. DEFE 24/1385. Another paper in this docket pointed out that the command at sea requirement had to be justified in the face of a trend towards exercising command of maritime operations from shore, using higher-capacity communications. At about the same time proposals were being made for the future automation of the Northwood maritime command centre. Points to be raised with the MoD Operational Requirements Committee included non-NATO scenarios and details of the limited command facilities aboard all other ships. Recent studies had shown that there had to be an Officer in Tactical Command afloat, well provided with command facilities. The navy’s position was that the three ship types were parts of an integrated package which was ineffective without the cruiser, its seaborne command and control and heavy-helicopter element. The Staff Target (the basis for the later Staff Requirement) was submitted for Board approval in August 1968.

2. Lillicrap Constructor’s Notebook 4 contains an estimate for a 30kt ship based on an ‘E’ class hull, to carry 250 mines: 510ft x 32ft x 16ft 6in, 6,700 tons (with 450 tons of oil). It needed 24,000ehp to make 30kts. The design, based on a ‘D’ class cruiser, had large trimming tanks fore and aft. Estimated dimensions were 450ft x 46ft (wl) 52ft (extreme) x 15ft, for a displacement of 4,900 tons without protection. The extreme beam was underwater, the ship having 4ft-deep bulges on each side.

4. Design history from a memorandum dated 25 April 1921 in Board Memoranda for 1921, ADM 167/64. Unfortunately the Adventure Cover has been lost, the Lillicrap Notebooks providing most of the design history.

5. As of 1 April 1921 Lillicrap was considering a 7,550-ton ship, 510ft (pp) x 59ft 10in x 15ft 6in, which would need 52,500shp to make the desired 28kts. He then cut back to 500ft x 59ft x 15ft 3in (7,150 tons), the size chosen, for which 55,000shp was needed. As built the ship had the standard wartime 40,000shp light cruiser plant, hence was somewhat slower than desired, about 27.5kts. The cut-back dimensions are the ones cited in the April memorandum.

6. Some notes on its design are in the summaries of Controller’s conferences in the Kent class Cover.

8. At this time Adventure was credited with 340 H (First World War) mines or 280 Mk XIV (current mines). Mines would be carried in four rows, two on each side of the ship, the mining deck being 464ft long (about 110ft longer than in Adventure).

9. W G John Constructor’s Notebook 11, instructions dated 20 October. John estimated that the ship would need 165,000shp. DNC also asked John to work up a design for an aircraft-carrying cruiser, perhaps inspired by the Swedish Gotland (and not too different in concept from the Japanese Tone), with three turrets forward, as in HMS Nelson, and one aft. She would carry three Walrus amphibians. Nothing seems to have come of this idea, which seems to have repeated a design estimate offered by Lillicrap in 1936.

10. Mines would weigh 558 tons, armament 436 tons, a very different proportion than in Adventure. Protection would have accounted for 390 tons. Machinery weight (2,587 tons) was based on comparisons with fast Italian cruisers. Later in the design, beam was reduced to 56ft, and desired mine load increased to 400 mines.

11. The specified mines were Mk XIVs, whose bogies used a broader-gauge track than the old H2, which in the late 1930s was still by far the most numerous mine in British stocks. Ships would therefore have a third rail (in storage) for every mine track, so that they could quickly be converted to lay the older mine.

12. As refitted in July 1945 Ariadne had three US twin Bofors instead of the two Hazemeyers, two of these guns being mounted aft to superfire over ‘X’ twin 4in. During the same refit, five single Bofors replaced the earlier ten Oerlikons. Apollo had fourteen Oerlikons, eventually replaced by six single Bofors.

13. On 2 December 1942 ACNS(W) asked the Future Building Committee to examine pros and cons. He pointed out that the ships had proved useful, though perhaps more as blockade-runners (particularly in the Mediterranean) than as minelayers. In later stages of the war they might serve both as minelayers and to supply advanced bases. Naval Assistant to Controller pointed to their low endurance at high speed, which ill-suited them to the long distances of the Far East. From a production point of view they were a nuisance, as they are a special type (large, of light construction) with special boilers, engines and propellers. They took disproportionately long to build and broke into any sort of production line. Slips for Ariadne and Apollo were being absorbed by an intermediate Aircraft Carrier (Hermes class) and two destroyers in January 1943; adding minelayers in 1943 would cut a carrier from the 1942 Supplementary programme and delay one in the 1943 programme by about six months, as well as delaying large destroyers. It was most uneconomical to build this sort of ship for use as a cargo carrier. Director of Plans pointed out that one ship (Latona) had been lost and another (Manxman) severely damaged by torpedo; these ships were subject to more than ordinary hazards. Offensive minelaying would certainly be useful against Japan, considering the large expanses of mineable water in the Far East. However, there were already minelaying destroyers, and the number available seemed sufficient for a balanced fleet. ACNS(W) gave up, but regretted that, ‘as we will want more once there is a probability that Japan is our only enemy.’ During the following year two more ships were lost: Abdiel to a ground mine and Welshman to a torpedo.

Some design work was done, as Brinton Constructor’s Notebooks 4 and 5 both contain calculations for either repeat Abdiels or for a new-design minelayer. Calculations for the repeat ship began in August 1942. Initially the main improvements would have been RPC for the 4in guns and, probably, additional electric power.