At 1100hrs on September 3, 1939, Britain declared war on Germany. One hour and three minutes later a Royal Air Force Bomber Command Blenheim of 139 Squadron took off from Wyton on the first operational sortie of World War II. Its task was reconnaissance of German naval ports, and to ensure accurate identification of vessels a Royal Navy officer was aboard. From a height of 24,000ft (7,270m), in perfect visibility, he noted three battleships, two cruisers and seven destroyers in Schilling Roads, off Wilhelmshaven.
The weather was deteriorating. Thundery atmospheric conditions and the long distance from base distorted the signal reporting the sighting and delayed further action until the Blenheim landed. At 1815hrs, nine Wellingtons of 37 and 149 Squadrons from Feltwell and Mildenhall, respectively, with 18 Hampdens of 49 and 83 Squadrons from Scampton and 44 and 50 Squadrons from Waddington, were airborne on what would have been the first British bombing raid of the war. Bad weather and nightfall frustrated them and they returned without having seen their targets. By 2240hrs the Wellingtons had touched down, and the Hampdens by two minutes after midnight.
The combined firepower of the battleships or the cruisers alone would have ensured that a force of 27 contemporary medium bombers was inadequate to sink or even damage severely one quarter of the 14 ships it was intended to attack. But these two formations were a generous provision out of Bomber Command’s modest total of up-to-date aircraft.
The RAF’s Order of Battle at home at that date was:
Bombers: 529 Battles, 338 Blenheims, 169 Hampdens, 160 Wellingtons and 140 Whitleys. The Battles were obsolescent and only the Blenheims and Wellingtons met contemporary performance requirements.
Fighters: 347 Hurricanes, 187 Spitfires, 111 Blenheims, 76 Gladiators and 26 Gauntlets. The biplane Gauntlets and Gladiators were obsolescent and the three-seater Blenheims, designed as bombers, were a makeshift as night fighters.
Coastal General Reconnaissance (GR) aircraft: 301 Ansons, 53 Hudsons, 30 Vildebeests, 27 Sunderlands, 17 Londons and 9 Stranraers.
Army Co-operation aircraft: 95 Lysanders, 46 Hinds and nine Hectors.
There were also Oxfords, Harvards, Harts, Tiger Moths and Blackburn D2s at training schools; Magisters, Mentors and Vega Gulls for communication; Henrys and Wallaces to tow targets for gunnery practice and to exercise anti-aircraft batteries.
The total of operational types was paltry compared with Germany’s. In particular the fighter strength was smaller than the Luftwaffe’s and even more outnumbered by the huge enemy bomber force against which it was to defend the United Kingdom. But, although Fighter Command was still at a numerical disadvantage when the Battle of Britain began ten months later, its numbers had grown and only one squadron of the obsolescent Gladiator fighters remained.
In Britain, flying by the armed forces began in 1912 with the formation of the Royal Flying Corps. It comprised two Wings: Military, under War Office control, and Naval, answerable to the Admiralty. In 1914 they separated and the Naval Wing became the Royal Naval Air Service. On April 1, 1918, both were combined to form the world’s first independent air arm, the Royal Air Force, with its own Air Ministry. (In 1924 the Admiralty created the Fleet Air Arm.)
The development of British military aviation was precipitated in August 1914, when Germany, ambitious to rule Europe, invaded Britain’s allies France and Belgium. The total aircraft strength of the Service was 179. When the war ended in November 1918 the RAF had 397 operational and training squadrons, at home and in France, Italy, the Middle East, India and Canada, with some 3,300 aircraft.
After the armistice the RAF quickly diminished as squadrons were disbanded, but its campaigning continued. No. 221 Squadron had been sent to Russia in 1918 to help the White Russians, who were fighting the Bolsheviks, followed by 47 Squadron in June 1919. In August, No. 221 returned home, then went to Somaliland in 1920 to put down a rising. No. 47 stayed in Russia until April 1920.
Britain had an empire to protect. The RAF maintained a higher level of training and a sharper state of operational preparedness than any other air force in the world and was gaining operational experience that was denied to anyone else. In 1923 the aircraft carrier Ark Royal took aircraft to the Dardanelles to prevent a threatened attack by Turkey against Greece, which would destabilise the Levant. These were joined by a squadron from Egypt, another from Malta and one from Scotland. Throughout the 1920s and 1930s the Service was responsible for keeping the peace in the Middle East, where aeroplanes were the only means of patrolling the vast desert areas, and in the mountains of the North-West Frontier, across which Pathan tribes constantly made armed forays into India. By January 1925 the RAF, most of whose aircraft were types that had seen service in World War I, consisted of 43 squadrons and four flying training schools, stationed in Britain, Malta, Iraq, Palestine, Egypt, Aden, Sudan and India.
It was organised in geographical commands: at home, Inland Area and Coastal Area (the RAF College at Cranwell and School of Technical Training at Halton also had Area status); overseas, Middle East (headquarters in Cairo), Iraq (HQ Baghdad), India (HQ Ambala) and Mediterranean (HQ Malta).
Of its squadrons, 10 were fighter, flying the wartime Snipe or Bristol Fighter and the 1924 Grebe or Siskin; 19 were bomber, operating the wartime DH9A or Vimy, and 1924 Fawn or Virginia; two were bomber-transport, equipped with the 1922 Vernon; and 10 were Army cooperation, with the Bristol Fighter. In 1927 the Air Ministry posted squadrons to Hong Kong and Shanghai; and to Singapore in 1928.
The Service was also pioneering in the wider practice of aviation. It carried mail between Britain and its army on the Rhine and between Cairo and Baghdad. It made long-distance proving flights, such as from the Cape to Cairo in 1925 and from England to Australia in 1927. Between December 1928 and February 1929 it carried out the world’s first large-scale airlift when 318 British and other European women and children, followed by 268 men from the British Legation and other diplomatic missions, were evacuated from Kabul.
Later in 1929 a specially built Fairey monoplane made the first nonstop England to India flight, in under 51 hours. In 1931, flying the Supermarine S6B from which the Spitfire was developed, the RAF set the world’s speed record at 407.5mph (652km/h) and won the Schneider Trophy outright for three successive victories in the biennial race. In 1933 it achieved the world long-distance record of 5,309 miles (8,494km), in 57 hours 25 minutes, non-stop between Cranwell and Walvis Bay, South Africa, again in a Fairey monoplane built to Air Ministry specification. In 1937, it broke the world altitude record with a climb to 53,937ft (16,344m) in a Bristol 138A. The RAF was experienced and a world-beater in aviation matters, with excellent equipment and highly trained personnel, but was unprepared for the tremendous conflict that was to come.
A minority of officer pilots, those who had graduated at the Royal Air Force College, Cranwell, were granted Permanent Commissions. The majority entered on Short Service Commissions that gave them four or five years with the regular force and four years on the Reserve. To ensure a civilian back-up on which to draw in an emergency, the Auxiliary Air Force was formed in 1925, to train air and ground crews at weekends and annual camps. By 1939 the AAF comprised 21 squadrons. Also in 1925, the Oxford and Cambridge University Air Squadrons were raised and in 1935 one at London University.
Nazi Germany’s depredations in Europe and Fascist Italy’s aspirations in Africa were a warning of imminent war that would involve Britain. In 1934 the RAF Expansion Scheme was announced. The Service now numbered 52 squadrons. These would be increased to 75. In 1935, when Italy went to war with Abyssinia, Britain moved three flying boat, four fighter and five bomber squadrons from their home bases to Middle East airfields from which they could protect Egypt, East Africa and Sudan. In 1936, with Germany and Italy even more aggressively on the rampage and threatening to provoke a conflict that would engulf the whole of Europe and spill over into the rest of the world, the Air Ministry took steps to increase the strength of regular squadrons to 136. In addition, it introduced a new stand-by pool, the RAF Volunteer Reserve, which aimed to train 800 pilots a year.
In May 1936, the RAF was restructured into four Commands: Fighter, Bomber, Coastal and Training. Geographical Commands, embracing the whole gamut of air operations, were retained overseas.
Fighter Command, with Air Chief Marshal Sir Hugh Dowding as Commander-in-Chief, had its Headquarters in Stanmore, a North London suburb. His immediately previous appointment had been on the Air Council as Member for Research and Development, so he was well acquainted with radar, an indispensable asset in his new post. Dowding had, as a captain, commanded No. 9 Squadron – formerly the Wireless Squadron – in 1915, on the Western Front. In 1916, as a major, he commanded No. 16, a scout – as fighters were called – squadron. Later that year, as a lieutenant-colonel, he took over 9th Wing. After the war he was successively Director of Training at the Air Ministry, and Air Officer Commanding-in-Chief, Transjordan and Palestine, before rising to the Air Council.
The Commands were sub-divided into Groups. In Fighter Command, these were on a geographical basis, further divided into Sectors, each named after its main airfield.
By the time the Battle of Britain was fought, Winston Churchill was Prime Minister of the Coalition Government. Sir Archibald Sinclair, leader of the Liberals, who had been Second-in-Command of Churchill’s battalion of the Royal Scots Fusiliers in World War I, was Secretary of State for Air. Air Chief Marshal Sir Cyril Newall, who, as a lieutenant-colonel, had commanded 9th Wing of the Royal Flying Corps, was Chief of Air Staff. During his three years and two months in the post, ending on 24 October 1940, he presided over the Service during the period of its most vigorous peacetime expansion. Marshal of the RAF Sir John Slessor described him as the ‘prime architect of the wartime Air Force’.
Dowding was the only one of the Command C-in-Cs appointed in 1936 who was still in office. His Groups were: No. 10, which began forming in January 1940 and was operational by the end of July, Headquarters at Box, Wiltshire; No. 11, Commanded by Air Vice Marshal (AVM) Keith Park, HQ Uxbridge, a London suburb; No. 12, Commanded by AVM Trafford Leigh-Mallory, HQ Watnall, Notts; No. 13, Commanded by AVM Richard E. Saul, HQ Newcastle-on-Tyne.
Bomber Command, under Air Chief Marshal (ACM) Sir Charles Portal, with Headquarters near High Wycombe, Bucks, was divided into Groups according to the type of aicraft they flew. The operational Groups were: No. 1, equipped with Battles, Headquarters at Hucknall, Notts; No. 2, Blenheims, HQ Huntingdon; No. 3, Wellingtons, HQ Exning, near Newmarket; No. 4, Whitleys, HQ York; No. 5, Hampdens, HQ Grantham, Lincolnshire. The Operational Training Groups were No. 5, HQ Abingdon, and No. 7, HQ Brampton, Huntingdon. For convenience, the stations in each Group were situated in as close proximity as possible. Portal had joined No. 8 Squadron as an observer in 1915 before converting to pilot. From C-in-C Bomber Command he went to Air Ministry as Chief of Air Staff until the Armistice. A wise and competent commander, he exercised much influence over Churchill.
Coastal Command was under ACM Sir Frederick Bowhill, who had joined the Navy in 1904, obtained his pilot’s licence in 1913 and entered the Royal Naval Air Service. With his understanding of naval needs, he was ideally fitted for his new post. His Command, which operated closely with the Navy, consisted of No. 15 Group, HQ Plymouth; No. 16, HQ Chatham; No. 17, HQ Gosport; No. 18, Pitreavie Castle, Scotland. None of these was related to any particular type of aircraft. Only No. 18 Group had any geographical connotation: its squadrons were all based in the north, mostly in Scotland and the Shetlands, with one in Iceland and two in Yorkshire.
Training Command had been split, in May 1940, into Technical Training and Flying Training Commands.
While Britain designed and built a wide variety of fighters and bombers in the two decades between the world wars, armament received scant attention. Most aircraft carried the rifle-calibre (.303 inch) Vickers gun of 1914–1918. The other RAF weapon, dating from 1916, was the American 0.3 inch Browning adapted for rimmed .303 ammunition. Fighters usually had two Vickers machine guns. The Gladiator, which entered squadron service in February 1937 and was the RAF’s last biplane fighter, was the first to be armed with a battery of four machine guns: they were Brownings. Its immediate successor, the Mk I Hurricane, entered service in December 1937 with eight Brownings, as did the Mk I Spitfire when delivered to its first squadron in June 1938.
These measures were not accompanied by an equally rational training programme for fighter pilots. The individual combat techniques developed in World War I were discarded. Combat practice was reduced to six set attacks made in section, flight or squadron strength. Air-to-air firing exercises were carried out on a drogue towed behind a comparatively slow aeroplane flying straight and level.
At the outbreak of World War II the RAF was highly efficient technically in both flying and maintaining its aircraft. It was experienced in the swift movement of squadrons from one country or continent to another. Among those who had served in World War I there reposed a substantial fund of expertise in full-scale war. In the Spitfire it had the world’s best fighter and in the Hurricane another that was in many other respects better than the enemy’s. But its numbers were comparatively small and its fighter combat training had been dangerously inflexible.
Numerical weakness was compensated for by possession of a unique adjunct to the country’s defence: a chain of radar stations that gave early warning of air raids. The word ‘radar’, standing for ‘radio direction and ranging’, was coined by the Americans and adopted by the RAF in 1943. Originally, it was called ‘RDF’, meaning ‘range and direction finding’, which was also good security; the process was thought to be concerned solely with radio direction finding as an aircraft navigation aid, which attracted little curiosity.
Development was carried out during the 1930s and exceeded the expectation of the Air Defence Sub-Committee of the Committee for Imperial Defence. On September 16, 1935, these bodies agreed that a chain of radio detection stations should be established between the Tyne and Southampton, to the number of about 20. These were to constitute ‘Chain Home’, referred to as ‘CH’.
The expected ranges at which these would detect aircraft were:
83 miles at 13,000ft (132km at 3,939m).
50 miles at 5,000ft (80km at 1,515m).
35 miles at 2,000ft (56km at 606m).
25 miles at 1,000ft (40km at 303m).
The original scheme envisaged a transmitting station every 20 miles (32km), alternate ones to have a receiver also. Each mast was to be not less than 200ft (60.6m) high, on land not less than 50ft (15m) above sea level and not more than two miles (3.2km) from the coast.
Range measurement by a transmitter-receiver station would fix an aircraft as lying in a certain circle. Measuring the time interval between the pulse transmitted by a neighbouring station would put the aircraft in a certain ellipse. Thus a transmitter-receiver with its two flanking transmitters could get a fix. Height finding was not to be introduced at first, although the height of an aircraft at 7,000ft (2,121m) altitude and 15 miles (24km) range had been measured to within one degree’s error in elevation (l,200ft/363m) by comparing signals received by two vertical aerials. In February 1936 the main experimental work was moved to Bawdsey, south of Orfordness, where a CH station was built. There, on March 13, a Hawker Hart was seen at a range of 75 miles (120km) at a height of 15,000ft (4,545m).
Trials in 1937 showed that most aircraft appearing in the observed area were reported with good accuracy up to 80 miles (128km); bearing was less reliable than range; height was good above 8,000ft (2,425m), unreliable below 5,000ft (1,515m). Estimates of the size of formations were not reliable. By the time the annual Home Defence Exercise was held in the summer of 1939, C-in-C Fighter Command Air Chief Marshal Sir Hugh Dowding reported: ‘The system worked extremely well, and although doubtless capable of improvements as a result of experience, may now be said to have settled down to an acceptable standard.’ At Easter 1939, with the outbreak of war expected at any moment, the radar chain had begun continuous watch-keeping. The Germans were curious about the tall towers that had sprung up on the English coast. In May General Wolfgang Martini, Chief of Luftwaffe Signals, flew up the east coast in the airship Graf Zeppelin, which radar picked up and, by the size and slow speed of the response on the cathode ray tube, identified. In August the airship, without Martini aboard, made a second sortie that radar did not detect, but which was seen by people in Scotland and intercepted outside the three-mile (5km) limit by a section of Auxiliary Air Force fighters. Both espionage ventures were abortive, as the Germans’ receivers picked up only a miscellany of confused noises that betrayed nothing about the existence of radar. Generalleutnant Adolf Galland has since revealed that right up to the Battle of Britain the Luftwaffe thought that the main purpose of the towers was the detection of shipping.
Chain Home operated on a wavelength of 10 to 13.5 metres, on frequencies of 22 to 30MHz, with 200kW peak power output. Its range was 120 miles (192km) and it could read height. The aerials were stationary, the transmitter was on a 350ft (106m) steel tower and the receiver on a 240ft (73m) wooden one. The coverage was described as ‘floodlight’, i.e., it was diffused in a wide arc or complete circle, which both inhibited the obtaining of accuracy in azimuth and allowed low-flying aircraft to go undetected. A shorter wavelength was needed to pick up at low altitude, and a rotating aerial to enable a narrow ‘searchlight’ beam to sweep from side to side or be pointed in any required direction.
Such equipment was devised and formed the Chain Home Low, or CHL. Its wavelength was 1.5m, frequency 200MHz, and power output 150kW. Range was 50 miles (80km) and it could not read height. The aerial, adapted from 200MHZ gun-laying radar that had also been designed at Bawdsey, was a gantry 20ft (6m) high, mounted on a 185ft (56m) tower.
The first CHL station began operating in November 1939. Mobile units were also being built. The vehicles on and in which they were installed became known as a ‘convoy’. The wavelength was 5.4 to 10m, frequency 30-56MHz, power output 40kW, range 90 miles (144km) and it indicated target height. The combined CH and CHL system gave the RAF an excellent probability of detecting virtually any intruders.
At the time of the 1936 reorganisation, the main question for Fighter Command was how to make the best use of radar. A control and reporting system (in RAF parlance ‘C & R’) had to be devised, to report the presence of enemy aircraft and control the movements of the fighters sent up to intercept them. Overall tactical control would be vested in Headquarters Fighter Command. Tactical control within each Group area would be delegated to Group Headquarters. Once fighters were airborne they would be controlled directly by their Sector. This meant that each Group and Sector, as well as HQ Fighter Command, had to have an Operations Room, in which the air activity within its area of responsibility could be shown. The general situation map (commonly referred to as the plotting table) in a Sector Ops Room needed to show the whole sector area and a large part of the adjacent sector or sectors. In a Group Ops Room, the whole Group area and part of the adjacent Group or Groups had to be displayed. In the Fighter Command Ops Room, a picture of the whole of the British Isles was necessary.
In addition to the CH stations, another source of information had to be integrated: the Observer Corps. This organisation originated in 1914 on the outbreak of World War I. The Royal Naval Air Service being responsible for home defence, the Police were instructed to report to the Admiralty by telephone when enemy aircraft were seen or heard. In 1916, the Army, of which the Royal Flying Corps was an arm, took over from the Admiralty. Cordons of civilian observers were now positioned at a radius of 30 miles (48km) around vulnerable areas, to inform the War Office when they saw or heard enemy aircraft and, if possible, to give an estimate of course and height. In 1921 the Observer Corps was restructured into observation posts that reported to observation centres reporting in turn to Fighting Area HQ, which was responsible for the defence of Great Britain.
By the time the RAF was restructured in 1936, the Observer Corps had grown in numbers. It took over from radar the tracking by sound and sight, and reporting, of aircraft when they crossed inland over the coast. The Observer Corps was a body of mostly part-time civilian members. At the end of the war the accuracy of their estimations was assessed most commendably. Height: visual, average error 10 per cent up to 20,000ft (6,060m); sound, 20 per cent. Strength: visual, exact; sound, good.
With three systems (Chain Home, Chain Home Low and the Observer Corps) reporting aircraft movements, a means of resolving disparities and duplication had to be found. Filtering was the name given to this process. At Bawdsey, an experimental filter room was set up in July 1937, to sort out the plots passed by the three CH stations then operating – Bawdsey itself, Dover and Canewdon (Essex) – and telling the filtered plots through to the Ops Room at Fighter Command during the annual exercise in August. On November 8, 1938, this was closed and the Filter Room opened at HQ Fighter Command.
A report from Bawdsey on August 30, after the annual exercise, noted:
‘Information is to be told to Groups and thence broadcast simultaneously to Sectors:
‘Experience with Biggin Hill has shown that Sectors require information accurately and speedily at a rate of one plot per minute per raid.
‘Information required by the three Groups will be obtained by at least 15 RDF stations, the observers (NB: the people who read the display on the cathode ray tube) at which, in time of high raid density, will tell plots at a high rate. This information is to be filtered and passed accurately and speedily to Groups and Sectors simultaneously. This means that on the average, when stations are all bringing in raids, the Group teller will have to tell information received from 5 RDF stations and will therefore have to tell information at five times the rate of the RDF observers.
‘A Sector requires information accurately and speedily at the rate of one plot per minute per raid. If each Sector can handle even four simultaneous raids, plots must be received at the rate of four per minute.’
No. 11 Gp had six sectors; Nos. 12 and 13 had three each. Hence the Filter Room had to pass plots at the rate of 12 per minute to Nos. 12 and 13 Gps, and 24 per minute to No. 11 if all Sectors were to be able to work to capacity. These were only the plots required by Sectors for interception, but there would also be information on distant approaching raids to tell.
In July 1940 Nos. 12 and 13 Gps each had six Sectors and No. 11 had eight. By the following month, with No. 10 Gp operational, three more Sectors were added. No. 10 in fact had four Sectors, but one of these had formerly been in No. 11, which now was reduced to seven. With four groups totalling 27 Sectors, it is clear why careful selection of radar operators, plotters and filterers was essential.
When the war began, the control and reporting system, the most sophisticated in the world, was fuctioning smoothly. By the time the first sorties in the Battle of Britain were flown, it had reached a degree of efficiency far higher than that of the equivalent German organisation.
The Women’s Auxiliary Air Force provided an increasingly large proportion of the personnel employed within it, at radar stations and Filter and Operations Rooms. This body, formed on June 28, 1939, was the successor to the Women’s Royal Flying Corps of World War I, which had become the Women’s Royal Air Force in 1918 and been disbanded in 1920. When three typists in the early days at Bawdsey had been trained to read and tell the responses on a cathode ray tube, it became apparent that women adapted better in many ways than men to this type of work.
The young women selected to be ‘Clerks, Special Duties’, their camouflaged job description, and known less pompously as ‘plotters’, had to have a higher than average educational standard. Predominantly, they belonged to the class that their comrades described as ‘boarding school girls’. To the pilots, who were supposed to visit the Ops Room frequently, in order to understand the difficulties of the Controllers’ job, they were ‘the beauty chorus’ and it was more the sight of a group of attractive girls than duty that drew the young men there.
The Observer Corps was organised in posts and groups. The system was fully tested during the exercise in August 1939. Secrecy about radar was so strict that, although the Corps was under the Air Ministry and received information from the radar chain, only a few officers were allowed to know the details of how this was obtained.
Posts were sited at any convenient place that allowed a good field of view: rooftops were good vantage points. They were not comfortable places in which to spend several hours at a time. In a small sandbagged enclosure with scant weather protection, equipped with an instrument for estimating height and position of aircraft, binoculars and a telephone, these dedicated men kept watch. Every group HQ had a centre where 12 plotters seated around a map table each received information from two or three posts, thus co-ordinating the efforts of about 30 posts.
Here again, the problem of duplication had to be resolved. A teller passed the plots to a maximum of six Fighter Sectors. An Observer Corps Liaison Officer was on duty at each Fighter Group. At the period with which we are concerned, there were some 30,000 observers, manning more than 1,000 posts radiating from 32 centres.
It was in the Sector Operations Rooms, ‘the sharp end’, that direct action against the enemy resulted from this nationwide and complicated network of interlocking data, which converged on the general situation map, the GSM.
An Ops Room had a thick concrete roof and surrounding blast walls. The main floor was some five feet (1.5m) below ground level. The GSM, with plotters wearing head-and-breast sets sitting or standing around it receiving filtered plots, occupied most of the space. With a long rod like a croupier’s rake, the plotters moved arrows representing a single aircraft or a formation. A wall clock was divided into five-minute segments successively coloured red, yellow and blue. The arrows forming a track corresponded in colour with the current segment. Thus the Controller could see whether it was fresh or stale. Beside the track was a small block with an identification letter and track number. ‘F’ in red on a white ground stood for ‘friendly’. ‘X’ in black on a yellow ground meant ‘unidentified’. A black ‘H’ on yellow was ‘hostile’. A plot was known as a ‘raid’, whether identified as friendly or hostile.
On the first tier of positions overlooking the GSM, running along one side of the large room, sat two NCO deputy controllers. On the next level, stepped slightly back, sat the Controller, a squadron leader in rank: in the early days of the war, this would be a pilot or observer, probably one who had flown in World War I. Gradually, to meet the growing need, non-flying officers were trained in the work. The Controller had two assistants: Ops B, a junior RAF or WAAF officer, and Ops A, usually an airwoman.
There was also a Royal Artillery anti-aircraft liaison officer, who warned anti-aircraft sites when friendly aircraft were near their area and ordered them to cease fire when any entered it and also tried to prevent friendly aircraft being illuminated to the benefit of the enemy.
On the wall facing the Controller’s dais were the clock, and the aircraft state boards on which the number of aircraft available in each squadron was shown, with the various states of availability to which the Group Controller had ordered them.
‘Stand-by’ meant that the engine had been warmed up and the pilot was strapped into his cockpit, ready to be airborne in two minutes. ‘Readiness’ called for pilots to run to their aircraft and take off within five minutes. The average time for a whole squadron to be off the ground was three minutes. The usual states of availability were 30 minutes or an hour, which meant that pilots had to be at their dispersal point on the airfield perimeter, either in the rest hut or, in fine weather, sitting outside it. Sometimes the Group Controller would order 10 or 15 minutes availability, or two hours, when pilots were allowed to be anywhere on the station (in their messes, if they wished). The final state was ‘Released’.
Ops A took instructions from Group – such as ‘One flight of 222 Squadron come to readiness’; ‘64 Squadron to 30 minutes’; ‘56 Squadron released’. He wrote this on a pink form and gave it to the Controller who, having read it, handed it to Ops B, who took action. For example, this might have involved calling the squadron concerned on the telephone and passing on the order.
Behind the Controller’s dais were four radio-telephony (R/T) cabins with WAAF, or airmen on listening watch. The transmitter was situated elsewhere within the station, on open ground. The HF receiver was in the cabin and the operator had the often difficult job of tuning it. When, late in the Battle, VHF began to be installed, the receiver was also remote from the cabin and kept tuned on site.
When one of the station’s squadrons was ordered to take off – singly, or as one section, or a flight, or the whole 12 – the Controller would speak to the leader on the R/T and tell him what course and height to fly and the enemy’s position, height, course and numbers, and all other essential information. He would try to direct the fighter(s) to the best position – up-sun – but usually the individual pilot or leader preferred to make his own tactical decisions. The Controller would continue informing and directing until contact with the enemy was made.
Mention has been made of Biggin Hill in connection with exercises carried out at Bawdsey. In 1936, No. 32 Squadron, stationed at Biggin Hill and flying Gauntlets, carried out the first exercises with the first embryo Sector Operations Room. It was as a result of these exercises that, with the pilots having the major say, the R/T code was drawn up.
All exchanges on the R/T were logged, so the operators had to write fast and use abbreviations: ‘V’ for ‘Vector’, ‘A’ for ‘Angels’, ‘T/H’ for ‘Tallyho’, a circle with a dot in the centre for ‘Orbit’, ‘RULC’ for ‘Receiving you loud and clear’. ‘R’ stood for ‘Strength’. If a message said, ‘Receiving you strength five’, it was logged as ‘RUR5’. ‘Target’ was ‘tgt’. ‘Are you receiving me?’ became ‘RURM’. ‘Listening out’ was ‘L/O’, and ‘Over’ was ‘O’.
The method of stating figures was also laid down. To avoid confusion, some were given in whole numbers and others in separate digits: Vector in separate digits (eg Vector one-five-zero); Angels in whole numbers (eg ten, fifteen, twenty-two) never in separate digits.
To avoid mishearing through heavy atmospherics or other interference on the R/T, a set pattern was used by controllers. In this way, pilots knew what the first, second, third, etc, parts of a faintly heard message must be about. First, the pilot had to be told his course and height: ‘Vector two-three-five, Angels twenty-one’. Next, where to look. The enemy’s relative position was given in clock code, taking 12-o’clock as dead ahead of the pilot: ‘Bandit(s) three-o’clock’. Then, how far away the enemy was: ‘Ten miles’. Then enemy height: ‘Bandit(s) angels thirteen’.
At the end of a message that required no answer, the caller, whether Controller or pilot, said ‘Listening out’ or ‘Out’. If an answer were required, the ending was ‘Over to you’ or ‘Over’. The ludicrous ‘Over and out’ much used in fiction would have been a contradiction. (The acknowledgments ‘Roger’, meaning ‘Received’, and ‘Wilco’ for ‘I will comply’, also misused in fiction, were US Air Corps terms adopted by the RAF in 1943 and unknown in the Battle of Britain.)
The TR9D HF transmitter-receivers in aircraft were of poor quality. Their range was rated 35 to 40 miles (56 to 64km) at 15,000ft (4,545m), although in ideal conditions this could be more. The set was vulnerable to all manner of interference, including BBC radio programmes. It had two channels, of which only one was available for voice. Each squadron operated on a different frequency. The second channel was common to all and used for the transmission of a 1,000-cycle note, a shrill whistle, code-named ‘Pipsqueak’, which sounded for 14 seconds. One aircraft in each formation was allocated a quadrant of each minute during which its pipsqueak would come on. While it was transmitting, the voice channel was cut off. The purpose of the device was to fix the position of a single fighter or a formation every minute. With VHF, voice transmissions were used and a good, experienced operator could take an accurate bearing in five seconds.
A sector had three direction-finding (D/F) stations sited at the corners of a triangle about 30 miles (50km) apart, each of which was tied by landline to a position at the fixer table, a much smaller version of the GSM and placed in the Fixer Room, off the main plotting hall. The site of each D/F station on this map table was surrounded by a compass rose marked in 360 degrees. A length of string was anchored at the site. As each station took a bearing on a pipsqueak, it passed it to a plotter who laid off the string along the given bearing. The point at which they intercepted was the fix, the position of the aircraft. A fourth plotter told this through to the GSM, where the fighter’s track was duly shown by a fresh arrow. If the cut was precise, it was a first class fix. If the strings formed a small triangle, it was second class and the centre of it was taken as the fix. If they formed a big one, it was known as a ‘cocked hat’.
This was the most useful way of showing the position of friendly fighters because the fix was obtained and plotted within seconds. One of a Controller’s most acute problems was that plots that had been through the filtering system were a couple of minutes late by the time he saw them on the GSM. During the interval between being picked up by radar or Observer Corps and plotted at Sector, aircraft had moved several miles and their relative positions might have altered drastically, making interception of a Hostile lengthy or impossible.
Pilots had individual two-figure callsigns, starting at 14 for the squadron commander, which were always given in separate digits. Sectors and squadrons also had callsigns, mostly of two syllables, which were changed from time to time for security. A typical call from the Controller to a single aircraft would be ‘Hello Tomcat One-Four. This is Locust calling. How do you read me?’ This would soon be abbreviated to ‘Tomcat One-Four from Locust. D’you read?’
When VHF became general and reception much clearer, with ranges of over 100 miles (160km) at 20,000ft (6,060m) in good conditions, messages became briefer. VHF aircraft sets had four channels with push-button selection. Two were guard frequencies on which a 24-hour listening watch was maintained for aircraft in trouble. Command Guard was common to all Fighter Command aircraft and Group Guard common to all those in that Group.
The four sections of three aircraft in a squadron were identified by a colour. This had no physical significance such as aircraft markings. ‘A’ Flight’s sections were Red and Yellow; ‘B’ Flight’s Blue and Green. When operating in section, flight or squadron strength, pilots’ callsigns would be their section colour followed by the number of their position in it. The Leader was ‘One’ (eg, ‘Red One’), his right wing man ‘Two’, and left winger ‘Three’.
Radio had also become a valuable source of intelligence before the war. The Organisation that provided it was the Y Service, which listened to German broadcasts and provided clues to the Luftwaffe’s strength, movement and intentions, helping the Intelligence Branch to compile the Luftwaffe’s Order of Battle. Coded messages were broken down at the Government Code and Cypher School, Bletchley Park.
At first the Y Service was confined to Morse transmitted by wireless telegraphy (W/T). In December 1939 steps were taken to begin listening to R/T on the 40 megacycle band. No suitable sets were made in England, so some Hallicrafter 510s, manufactured in the USA and popular among radio ‘hams’, were bought and set up in a hut at Hawkinge by March 1940. Two months later the first message was picked up. Only then did anyone realise that none of the operators knew German. A German-speaking soldier on an anti-aircraft site at the airfield was found and rushed to the R/T receiver, and willy-nilly transferred to the RAF within days.
What was really needed were not people who had studied German academically but those who had lived in Germany and acquired a command of idiom. Recruiting from within the WAAF began immediately and by June 15 six airwomen had been posted to a new listening site at Fairlight near Hastings, equipped with two Hallicrafters.
Experienced RAF wireless operators searched the air for traffic and as soon as a transmission was picked up a WAAF interpreter would take over and log it. Anything of immediate tactical significance was passed at once to No. 11 Group.
Much of the traffic was from E-boats (Schnellboote, or fast boats, known logically to the Germans as S-boats and bizarrely to the British as above), and this was forwarded to the Admiralty via Air Ministry. Less urgent material was sent to Air Ministry for analysis. The girls quickly learned the Luftwaffe R/T code and became familiar with individual enemy fighter pilots by their callsigns, accents and personalities. They recorded exchanges between fighters and bombers attacking airfields and convoys, and reports from reconnaissance aircraft when convoys were sighted. These last were passed to the naval authorities at Dover as well as to No. 11 Group.
Increasing knowledge of the callsigns and frequencies used by the Luftwaffe enabled the listeners to warn No. 11 Group of the Geschwader and the type of aircraft involved in an imminent attack. Some of the intercepted messages even gave the time, height and place for a rendezvous between fighters and bombers, and their target. Y intelligence was also a useful means of cross-checking reports of enemy casualties, when, in the speed and confusion of a fight, more than one pilot claimed the same victory.
Among the less salubrious events recorded were the occasions when British pilots commented on comrades being shot at by the enemy’s gallant fighter pilots while parachuting out of aircraft they had been forced to abandon. Added to the use for reconnaissance of supposedly ambulance aircraft, allegedly on air-sea rescue missions, and the strafing of civilian refugees on French roads, which was also frequently reported, the RAF was inclined to be cynical about the Luftwaffe’s boast that it was fighting a clean and chivalrous war.
To provide accommodation for more sets, six more WAAF and additional RAF wireless operators, the unit was moved to Hawkinge in July. Towards the end of that month it was they who intercepted messages indicating that the enemy was using aircraft marked with the red cross on reconnaissance over the Channel. Air Ministry duly warned the German High Command that such aircraft would no longer have immunity; as related elsewhere, Ginger Lacey was among the pilots who shot one down,
By August, the unit moved again, to a small house and adjacent toy factory at West Kingsdown on the Kentish Downs, the highest point in the county, which increased the range of the R/T receivers. The other Fighter Groups soon asked for the same information as No. 11 Group was getting. The listening posts were given the name ‘Home Defence Units’ (HDU) and by the time the Battle of Britain was coming to an end new ones had been set up at Street, Devon, for No. 10 Group; Gorleston, Norfolk, for No. 12; and Scarborough, Yorkshire, for No. 13. An HDU was also placed on Beachy Head as a back-up to Kingsdown – which had become the HQ of the Y Service – to concentrate on raids against convoys and southern airfields and ports.
The examination of enemy aircraft that crashed in Britain, the interrogation of captured aircrew, and agents in Germany were other sources of intelligence, but the most prolific and versatile was photographic reconnaissance. This was one of the earliest uses to which aeroplanes had been put in World War I, yet Britain allowed it to languish in the inter-war years. It was indispensable in the planning of both strategy and tactics. In 1938 General Werner von Fritsch, Commander-in-Chief of the German Army, said, ‘The military organisation that has the best photographic intelligence will win the next war.’ The RAF School of Photography at Farnborough was formed in 1912, but in the 1920s and 1930s its skills were turned mainly to the photographing of British colonial territories for map-making. The system was cumbersome. All three of the armed Services required aerial intelligence: the RAF took the photographs, but only the Army had photographic interpreters. It took a week for the results of a sortie to be delivered.
When, in 1936, information about German industry was sought, a squadron leader was sent to Germany to collect photographs and maps. It was only when Wing Commander F. W. Winterbotham, Chief of Air Intelligence in the Special Intelligence Service, wanted specific information about the Luftwaffe’s air defence of the German frontier that aerial ‘photo recce’ or ‘PR’, as it was called, began to be used. In cooperation with the French intelligence organisation, the Deuxième Bureau, the right man was found to take on the work.
F. Sidney Cotton was an Australian pilot who had done pioneering work in Canada and Greenland and over the Atlantic. In 1938 the colour film business he owned failed. He accepted the task of spying on Germany and a company named Aeronautical Research and Sales Corporation was formed as a cover. The aircraft had to be one that could fly on ostensibly legitimate civil business. Cotton chose a Lockheed 12A, which could carry six passengers, and one was delivered in January 1939. He asked for a first-class engineer who was also a pilot, and a Canadian in the RAF, Flying Officer R. H. Niven, was selected. The Deuxième Bureau provided a photographer and on March 25th the operation was based at a pretty little airfield 15 miles (24km) south-west of Paris, Toussus-le-Noble.
Cotton and his crew made their first flight on March 30, over Krefeld, Hamm, Münster and the Dutch frontier to photograph the road and rail systems. More flights were made on April 1, 7 and 9, covering the Black Forest, armament factories and new aerodromes in the Mannheim area and the Siegfried Line. There was no intercommunication between cockpit and passenger cabin. Monsieur Blois, the photographer, tied a long string to each of Cotton’s elbows and tugged the appropriate one to indicate the direction in which to turn! They also made flights over Italy and the North African coast.
One man who knew that special equipment and training were needed for first class PR was Air Chief Marshal Sir Edgar Ludlow-Hewitt, who had joined the RFC in August 1914 and served at the Western Front throughout World War I. When appointed C-in-C Bomber Command in September 1937 he had stated the need for a special long-range reconnaissance aircraft. But the Service showed little interest and, anyway, the Defence Budget could not afford it. He had to compromise by fitting cameras to the Blenheim bombers of Nos. 21, 82, 107, 114 and 139 Squadrons. In 1938 the Air Ministry did, under pressure from him, set up the Air Intelligence Department to co-ordinate PR. In 1939 an Air Intelligence Section was introduced at HQ Bomber Command and Station Intelligence Officers were made responsible for a preliminary interpretation of photographs.
In the summer of 1939 Cotton and Niven flew to Germany allegedly to sell colour film. His camera was installed under the cabin floor in a dummy fuel tank. This ruse enabled him to fly all over the country, sometimes with German passengers, taking photographs of enormous value. Two weeks after the outbreak of war, when Blenheims on photographic sorties had suffered casualties without achieving adequate results, Sir Cyril Newall, Chief of Air Staff, authorised Cotton – who was in due course commissioned in the RAF and rose to be a wing commander – to form and command a specialised unit, for which he would select his own personnel, aircraft and equipment. Based at Heston, it was named Photographic Development Unit (PDU).
Dowding had been greatly impressed by Cotton’s achievements and, in October, agreed to lend him two Spitfires so that undetected reconnaissances could be made at a height above the limit of heavy flak (25,000ft/7,575m), at a speed greater than the Bf 109. These Spitfires had to be stripped of guns and ammunition to reduce weight and allow adequate range and height. From take-off the aircraft could attain 30,000ft (9,090m), and as they consumed fuel their ceiling rose to 35,000ft (10,600m). They were camouflaged duck egg blue to merge with the sky and relied on speed and stealth for survival.
The first Spitfire PR sortie was flown on November 18, 1939, and revolutionised the whole concept of this means of intelligence. The Spitfires flew only 15 flights but achieved twice as much, in half the time, as seven Blenheim squadrons. Between September 3 and December 31, 1939, the Blenheims had flown 89 sorties over 2,500 square miles (6,475km2), obtained photographs on only 45 sorties and lost 16 aircraft. In just 15 sorties, the Spitfires came back with photographs on 10 and covered 5,000 square miles (12,950km2) without loss. By the end of February 1939 Cotton had three Spitfires, one of which was for training.
In bad weather, the recce Spitfire’s solitary pilot was handicapped by lack of navigation instruments: of 19 sorties flown in the first quarter of 1940, weather made 13 ineffective. The PDU acquired three Hudsons in February, to reconnoitre above cloud the weather along a Spitfire’s intended route and report by radio. If conditions were unsuitable for a Spitfire, the Hudson would descend below cloud and take the photographs.
On July 8, 1940, as the Battle of Britain was about to be fought, the PDU became the Photographic Unit of the RAF and command was given to Wing Commander Geoffrey Tuttle.
Among the most valuable items of intelligence garnered by the RAF was one that was delivered from the enemy side. In the early hours of November 5, 1939, a parcel was left outside the British Consulate in Oslo with a letter signed, ‘A German scientist who wishes you well.’ In it were a proximity fuse for anti-aircraft shells, details of the new Junkers 88 and its intended use as a high-speed dive bomber, an account of German rocket development and a description of the device known as Y-Gerät that enabled German bombers to find their targets by following a beam.
A final gift to Britain’s benefit was possession of a machine that could decypher German codes. It was invented in Holland and the patent was bought by a German manufacturer in 1923. It was discovered by Polish Intelligence when Customs examined one that had been sent to the German Legation in Warsaw. In 1934 the RAF began development of this machine, known as the Typex, which the Government Code and Cypher School had bought in 1928 and neglected. In August 1939 the Poles gave the British the result of their work in breaking the latest German codes.
The Germans had called their first encyphering machine ‘Enigma’ and the British gave this name to all German cyphers. ‘Ultra’ was the British codename for intelligence derived from Enigma and other machine cyphers. The only two commanders in the RAF who knew of Enigma and Ultra were Dowding and No. 11 Group’s Air Vice Marshal Keith Park. A specific instance of its importance in the Battle of Britain was that the heavy air raids on August 15, 1940 did not take these two senior officers by surprise. The information given to them was precise: Luftflotten 2, 3 and 5 would make the attacks, which were timed to keep the defenders at full stretch throughout the day. F. W. Winterbotham, who, as a group captain, was responsible for Ultra, recorded that Dowding told him that it was of the greatest help to him to know what Goering’s policy was and enabled him to use his fighter squadrons with the greatest possible economy.
Fighter Command entered the Battle of Britain with an infrastructure that provided increasingly skilled and detailed intelligence and a Ministry of Aircraft Production that achieved an output of fighters much in excess of the scheduled number. It was closely integrated with Anti-Aircraft Command, which comprised seven divisions with an establishment of 2,232 heavy and 1,860 light guns, and 4,128 searchlights, under Lieutenant General Sir Frederick Pile.
The third weapon of defence was the barrage balloon. On November 1, 1938, Balloon Command had been formed and expanded with Auxiliary Air Force balloon squadrons. It operated in three Groups. No. 31 Group consisted of Nos. 901 to 910 Squadrons, numbering 450 balloons. No. 31 Gp squadrons were Nos. 911 to 926, with 456 balloons. No. 32 Gp squadrons were Nos. 927 to 935, totalling 224 balloons. No. 33 Gp squadrons were 936 to 947 squadrons, with 320 balloons. As would be expected, the RAF’s Order of Battle changed many times during the Battle of Britain, as shown in a later chapter. A secret document, ‘State of Aircraft in Operational Commands’, was issued every week.