This was the seminal report by my father, published in the first issue of Intelligence & National Security on which many historians of signals intelligence have relied He wrote it shortly after his retirement and my mother typed it on her ancient typewriter.

I

In paragraph 10 of ‘Post-War Intelligence’, a memorandum by Group-Captain Jones, occurs the remark in large type:

It would indeed be a tragic and retrograde step for intelligence as a whole, and therefore – this is not putting it too high – for the future of the country, if GC&CS were to sink back into its pre-war position.

I think I am right in taking these words not as a general scathing criticism of the pre-war activities of GC&CS but as a warm tribute to the efficiency of the wartime development in GC&CS of its new function of ‘Intelligence’ at the source, a tribute with which, I am sure, none of the service departments will quarrel.

But in justice to the late Admiral and to the members of the peace reorganization of GC&CS who, for 20 years fulfilled their allotted task and reached 1939 with a solid foundation on which to build, I propose to state quite briefly for the information of those now about to build a new GC&CS:

A The origin and purpose of the 1919 GC&CS;

B Its establishment under Treasury control;

C Its development.

Files and records sent to safety in 1940 are not available to me, therefore I write from memory and cannot claim complete accuracy in dates and numbers. But the main facts can be substantiated by the evidence of others who took part during those 20 years.

 

II

A [THE ORIGIN AND PURPOSE OF THE 1919 GC&CS]

1. During the 1914-18 war cryptography was practised in two sections:
(a) 40 OB, principally German naval, latterly a certain amount of diplomatic enemy and neutral, only using material obtained by interception of W/T by stations under Admiralty control, and
(b) MI 1B, principally German military and (currently) some neutral and later even Allied diplomatic, the raw material for the latter being obtained from Cable Censorship under War Office control. Only from 1917 was there any exchange between (a) and (b) and then principally of results.

2. Early in 1919 the Cabinet decided that the results obtained by these two sections justified the formation of a permanent section to keep alive the study of this work which had such an important effect on the prosecution of the war, both naval and military.

3. Admiral Sinclair (then DNI) was given the task of forming a section from the remnants of 40 OB and MI IB, to be established under the civil administration in the Admiralty. Negotiations between Admiralty, War Office and Treasury continued through spring and summer of 1919 and in November or December the new organisation was set up in Watergate House (staff details under B).

4. The present [1944] Ambassador to Peru (Courtenay Forbes), then in the Communications Department of the Foreign Office, invented the title Government Code and Cypher School.

5. The public function was ‘to advise as to the security of codes and cyphers used by all Government departments and to assist in their provision’.

6. The secret directive was ‘to study the methods of cypher communications used by foreign powers’.

7. Nothing in this constitution indicated how raw material was to be obtained. But DNI, being in charge, was able to retain a small party, both in the Admiralty and War Office, drawn from their rapidly diminishing war time intercepting stations. Pressure from DNI and others procured the inclusion in the New Official Secrets Act of a clause instructing all cable companies operating in UK to hand over for scrutiny copies of all cable traffic passing over their systems within 10 days of despatch or receipt.

8. Nothing in the constitution indicated that it was desirable that successful results of the study should be made available to government departments who might be interested, though in actual practice there was a circulation of ‘unprocessed’ decodes from the day of our birth, which has continued until today without interruption.

9. In 1921 the Geddes axe fell on us and we moved to Queen’s Gate where we were more comfortable but rather remote from other departments. But we were nearer Melbury Road, and when the Admiral took over in 1923 he, as our founder, at once took steps to bring the two organisations into closer touch; this process culminated in 1925, when both moved to the third and fourth floors of Broadway Buildings.

10. About 1922 after two or three years’ work and circulation in which results showed that there was no service traffic ever worth circulating, the late Lord Curzon, then Foreign Secretary, claimed that GC&CS was doing work solely for the Foreign Office and should therefore be transferred from the Admiralty to the Chief Clerk’s Department of the Foreign Office for administrative purposes. The Admiralty, at that time in process of cutting down, willingly assented and thenceforward GC&CS estimates appeared in the Foreign Office vote.

11. It must be remembered that beyond a salary and accommodation vote GC&CS had no financial status; it became in fact an adopted child of the Foreign Office with no family rights, and the poor relation of the SIS, whose peacetime activities left little cash to spare.

 

III

B [ESTABLISHMENT OF GC&CS UNDER TREASURY CONTROL]

1. GC&CS began with a sanctioned establishment of 25 pensionable officers as follows:

A clerical staff (unpensionable) was also sanctioned, amounting to approximately:

2. The pay of the senior staff was based on that of the Administrative Class in the Civil Service, that is:

In due course members of our staff were considered to be eligible for membership of the Association of First Division Civil Servants as are the senior staff in the museums, but there has never been any question of precise equality of pay.

3. On the other hand, when we had to recruit new staff through the Civil Service Commission our candidates did not have to sit for the Administrative Class examination but were selected on interview and record by the Committee of the Commission in which GC&CS was represented.

4. The original selection in 1919 for all classes was made from volunteers who had served in the Admiralty or War Office. Where the needs of the work required special qualifications such as Japanese (Mr Hobart-Hampden) or a highly experienced but already elderly man (Mr Fetterlein) who could not be made pensionable, they were granted equal pay with the others and blocked posts in the establishment. The Chief Clerk had difficulty more than once in explaining to the PAC why two very senior ex-Foreign Office officials were now graded as junior assistants of the GC&CS.

5. In 1925 when we first recruited young staff direct from the university, the establishment was increased to 10 seniors and 20 juniors. But promotion was slow. Naturally there was little or no difference in the work of good juniors and seniors. Therefore during the early 1930s the proportion was altered to 15 seniors and 15 juniors.

6. But promotion was still too slow, principally because no seniors died nor were superannuated. Therefore in 1937 the Treasury agreed to promotion of junior to senior after 10 years’ service and the scales were slightly altered and fixed at:

while the head and deputy head were given the position and pay of assistant secretaries.

7. The above paragraphs (B, 1-6) have concerned the civil staff established under the Foreign Office. It might be fitting now briefly to account for the contribution made by the Services (Admiralty, War Office and [later] Air Ministry).

8. Their main effort was in the interception of foreign government W/T messages, a subject outside the scope of this paper. But the Admiralty and the War Office did make some staff contribution to the GC&CS until the time when the War Office and Air Ministry did maintain their own section within the framework of GC&CS.

9. From 1923 onwards the Admiralty evinced special interest in the Japanese diplomatic and naval attaché traffic and always provided one officer (Japanese interpreter) to work in the section. When a small party in the Far East was being formed, a system of rotation arose. Ultimately when in 1934 Admiralty started a bureau in Hongkong, sufficient officers had been trained to man it and Paymaster-Captain Shaw (then retired) was taken on the Foreign Office Establishment to act as the first head of the bureau. Further Admiralty assistance in the matter of staff is described in part C.

But the Admiralty, unlike the other two services, never maintained their own section in GC&CS.

10. The War Office, at the time of the Armistice, had in addition to MI IB, certain small sections overseas of which the one in Constantinople continued to function after 1918 until its staff were transferred (about 1922) to form the original nucleus of the War Office station at Sarafand which still exists today as an intercepting and crypto-graphic unit dealing almost entirely with local problems. A close liaison between GC&CS and Sarafand has always been a satisfactory feature. During the twenties the War Office did send military officers to GC&CS for some training before proceeding abroad. Among others, Captain Tiltman, spent some months in 1920 at Watergate House on his way to the Middle East. But it was not until the early troublous thirties that Captain Tiltman, having returned from a long tour of duty in India, rejoined us, and before long started, himself as a civilian under the War Office, the Military Section to which were attached an increasing number of military officers. Their activities will be described more fully in [part] C.

11. For at least 15 years of our life the Air Ministry, while considerably interested in some of our results, contented themselves with the provision of valuable intercepting facilities. But about 1936 their Intelligence authorities felt the need of a technical expert of their own. They therefore set up the RAF Section within the framework of GC&CS and Mr J.E.S. Cooper was transferred from the Foreign Office to the Air Ministry civil establishment. The early development of this section will also be dealt with more fully in [part] C.

12. During 1937 the Admiral, convinced of the inevitability of war, gave instructions for the earmarking of the right type of recruit to reinforce GC&CS immediately on the outbreak of war.

Through the Chief Clerk’s Department we obtained Treasury sanction for 56 seniors, men or women, with the right background and training (salary £600 a year) and 30 girls with a graduate’s knowledge of at least two of the languages required (£3 a week).

To obtain such men and women I got in touch with all the universities. It was naturally at that time impossible to give details of the work, nor was it always advisable to insist too much in these circles on the imminence of war.

At certain universities, however, there were men now in senior positions who had worked in our ranks during 1914-18. These men knew the type required. Thus it fell out that our most successful recruiting occurred from these universities. During 1937 and 1938 we were able to arrange a series of courses to which we invited our recruits to give them even a dim idea of what would be required of them. This enabled our recruits to know the type of man and mind best fitted and they in turn could and did earmark, if only mentally, further suitable candidates. These men joined up in September 1939.

Thus very early in the war GC&CS had collected a large body of suitable men and women quite apart from recruitment of service personnel by the two service sections, of which the Military was now on an entirely military footing.

13. With regard to the clerical and typing staff which grew gradually during those years, involving us in prolonged discussions with the Treasury, the Tomlin Civil Service Commission of 1929 widened the basis of establishment, consequently we did obtain sanction for the establishment of two higher clerical, some six to ten clerical officers, about a dozen clerical assistants and half a dozen typists.

By this means we were able to retain with prospects of pension some of those girls and women who had proved their value to us in both our functions.

 

IV

TOP SECRET

C [DEVELOPMENT 1919-1939]

1. In A.5 I stated that the ostensible function of GC&CS was ‘to advise as to the security of codes and cyphers used by all government departments and to assist in their provision’.

This duty was carried out exclusively by Travis who came to us fresh from this type of work in the Admiralty, together with a clerical party whom he had trained. He alone is in a position to tell the story of its development.

Suffice it to say that each of the big departments nominated officers in the Communications Branch to act in liaison with us. The Admiralty alone appointed an officer to work in GC&CS (later increased to two officers). Out of this has now grown the section known as CSA with far wider responsibility and power.

2. The secret side of GC&CS had as its task ‘to study communications of foreign governments’.

The development of this work I propose to outline under the headings Diplomatic, Clandestine, Services and Commercial in the order of their appearance as vital issues during the period 1919-1939.

3. Diplomatic

As stated in A, 1 and 2, some diplomatic work was undertaken in both sections during the 1914-18 war. But it must be emphasised that this work was from a cryptographer’s standpoint most elementary. Of the countries then tackled and read, only the German Foreign Office was using ‘hat’ books and reciphering methods: all the others read had an alphabetical basis. Sir George Young invented a method of reading German hat books (for which he received a monetary reward) which included an elaborate card index manned by some ten graduate women. Within a year of the start of GC&CS, the solution of a hat book was the task of one good linguist working on the method used by Mr Fetterlein for many years in this work in Russia. I myself, working with Young, also received a monetary reward for solving the first additive key we had ever seen as used by the Germans. When I say that this key varied from 7-13 digits, I must consider myself lucky to have been rewarded for a job which nowadays any young cryptographer would take in his stride.

Fetterlein’s previous training enabled us to read the fairly complex Austrian keys and rebuild their hatted books.

It might perhaps be noted here that I took a small Admiralty party over to Paris, in April 1919, to work with the French on the German material passing during the Peace Conference. We remained until the signing of the Peace of Versailles and I have always thought that our visit was useless though pleasant. Although Germany was a beaten nation, nothing appeared in the terms of Armistice concerning their diplomatic cyphers. Consequently their mission came to Paris provided with entirely new books and methods. We obtained all the traffic between Paris and Berlin but failed to produce anything of any value. How could we? Germany knew well we had read her diplomatic traffic for the last three years (e.g. Zimmerman Letter), and no one prevented Germany from replacing her compromised codes by the safest methods she could devise. I believe that at that time Germany made use of OTP for the first time. I am certain she used the method ultimately solved in 1942 and then only thanks to an amazing scrap of physical compromise. In any case there was no GC&CS at that date and such was the lack of co-ordination that the party in Paris never saw results obtained in London of American and Japanese work, while French and Italian had then never been attempted.

All other powers which were read in wartime, including American, Japanese, Greek, Spanish and Scandinavian, were using alphabetical books. Norwegian was alphabetical; the first Danish and Swedish solved were hatted but some ‘cribs’ were available.

Thus it came about that in 1919 only those who had worked on the enemy countries, who were driven to recyphering processes, had had any real experience in cryptography. The majority of the party were linguists. Ultimately the reconstruction of code books used and the translation and emendation of the resultant texts was our productive function. Fetterlein, Strachey and Knox were our original key men while Turner had the role of master-linguist with Hobart-Hampden in charge of Japanese.

The first effort of the early years was devoted to breaking into the hitherto untouched material from various governments.

a. The Americans celebrated the advent of peace by introducing a new hatted diplomatic code recyphered with tables changing quarterly. The solution of the first of these tables was a year’s work and thereafter the American Section had to be expanded for the increased task of breaking the tables and reconstructing the code. Good progress was made, and the section was able to be of some assistance during the Washington Naval Conference in 1922.

b. The second really big task was to make a concentrated attack on French diplomatic cyphers, which had received no attention during the war.

A large number of hatted books of 10,000 groups were used and with the constant practice of reconstruction of such books they never presented any difficulty. Given sufficient traffic, legibility appeared within a month of birth.

Many recyphered books also appeared and after the initial struggle to obtain the general system, the constant change of tables presented little difficulty. Only about 1935 did the French introduce any system which defied solution. This was a development of the bigrammatic substitution and it was felt that even this would not be insoluble if only there were enough traffic. The Quai d’Orsay is conservative and we never observed anything of the OTP type.

The reading of this traffic during the years of peace and intrigue did from time to time produce very interesting if not invaluable intelligence. But the proximity of the two capitals did mean that a great deal passed by bag.

c. The only real operational intelligence came from our work on the Soviet traffic. We were able to attack their systems step by step with success from the days of Litvinov’s first visit to Copenhagen, of Kamenev as their first representative in London followed by Krassin, until the famous Arcos Raid in 1927 (?) when HMG found it necessary to compromise our work beyond any question. From that time the Soviet government introduced OTP for their diplomatic and commercial traffic to all capitals where they had diplomatic representatives.

The revolutionary government in 1919 had no codes and did not risk using the Czarist codes which they must have inherited. They began with simple transposition of plain Russian and gradually developed systems of increasing difficulty. The presence of Fetterlein as a senior member of the staff and two very competent girls, refugees from Russia, with a perfect knowledge of the language, who subsequently became permanent members of the staff, enabled us to succeed in this work. We were also able to borrow certain British Consuls who could not return to Russia.

d. The fourth big productive effort was on the Japanese. Here the cryptographic task was for the first ten years almost non-existent so far as diplomatic work was concerned. For the language, which was the main difficulty, we were lucky enough to have recruited Hobart-Hampden just retired from 30 years’ service in the East. But for a long time he was virtually alone, but with his knowledge of the habits of the Japanese he soon acquired an uncanny skill in never missing the important. Probably not more than 20 per cent of the traffic received was circulated, but throughout the period down to 1931 no big conference was held in Washington, London or Geneva in which he did not contribute all the views of the Japanese government and of their too verbose representatives. Sir Harold Parlett, another distinguished officer from the Japanese service, joined him in 1926 and ably seconded him with an equal sense of the essential. Yardley’s ‘Black Chamber’ tells of the American success at the Washington Conference. No one will ever tell how much accurate and reliable information was made available to our Foreign Office and Service Departments during those critical years.

Of the building up of the Japanese naval work, in which both these officers played a part, I will be speaking briefly later.

e. A continued watch was kept on the ex-enemy countries, but here there was little development. Germany was allowed to introduce her new methods, and we soon knew that she was using OTP for all she wished to keep secret. In course of time we knew her method of using pads and how she made them up. We also knew of her second method and diagnosed it as unbreakable.

This second method, nicknamed Floradora, was finally broken in 1942 thanks to three chances:

We had in fact reconstructed the basic book during the period 1932-39, but the effort was never profitable as German security rules forbade its use unrecyphered, except for purely administrative telegrams which proved of little interest or value.

The Austrian government had always used reasonably secure methods of recypherment and never used their books plain. Thanks to assistance from Fetterlein we did read them in 1918 and 1919, as there was sufficient traffic. But Trianon produced a small poor country whose communications grew less and less, and ultimately we failed for lack of telegrams.

Austria, Hungary, and the Balkan countries rarely produced sufficient material to justify an attack. The greater part of their telegrams probably passed on the continental landlines which were never available to use in peace.

Hungarian was successfully tackled by Knox, but it is doubtful if the results obtained at that time justified the enormous effort on his part.

Later an increase in the use of W/T and the troublous political situation did enable us to read some of the traffic of these countries but never have we been able to report full legibility, a regular flow of traffic and valuable results.

f. Some of the other powers had already been started in MI 1B or 40 OB, notably Greek, Spanish, Italian, Scandinavian and Persian and where purely alphabetical books were used, telegrams had been read and circulated.

Sections were therefore formed in the new GC&CS to carry on this work. Early in our career the Foreign Office disclaimed any interest in Scandinavian, so this subject was dropped.

Passage of time and changes in the political situation opened up new lines. The various South American republics, Portuguese, Brazilian, were tackled. The Balkans were watched, though little traffic was available as European landlines carried most of it. A Near East Section was envisaged, working in close co-operation with the military station at Sarafand, of which I will write later.

To sum up the cryptographic effort of 20 years on diplomatic traffic: we started in 1919 at the period of bow-and-arrow methods, i.e., alphabetic books; we followed the various developments of security measures adopted in every country; we reached 1939 with a full knowledge of all the methods evolved, and with the ability to read all diplomatic communications of all powers except those which had been forced, like Germany and Russia, to adopt OTP.

The authority who sanctioned our establishment in 1919 clearly never envisaged a complete reading, translation and issue of every telegram received by us.

Such was a physical impossibility for the 30 specialists who composed the main body of the staff employed on the work.

Hence from the outset sections did exercise their own discretion as to what they translated and submitted for circulation. They got guidance from the D and R who in turn received intelligence directives from the Foreign Office, the circulating sections of SIS and the officers who used our material in the Service and other large departments.

During the thirties we did supplement our daily issue by a daily ‘Summary of telegrams decoded but not circulated’, for the benefit of SIS, Admiralty and War Office (occasionally the Foreign Office) and it is noteworthy that it was only a very small percentage that were ever asked for in complete form.

With personal satisfaction I maintain that GC&CS did during those 20 years fulfil its allotted function with success, with exiguous numbers and with an absence of publicity which greatly enhanced the value of its work.

4. Clandestine

Peacetime GC&CS did have one experience of successful work on clandestine traffic. This, unlike the diplomatic, necessitated close cooperation between interception, T/A and cryptography before the final results were made available only to a small select intelligence section of SIS.

Some time around 1930 our stations picked up a mass of unusual and unknown transmissions, all in cypher except for the ‘operators’ chat’, which was all of the international amateur type. The analysis of this traffic was studied closely, and from it emerged a worldwide network of clandestine stations controlled by a station near Moscow. It turned out to be the Comintern network. Brigadier Tiltman has written up the story of the cryptography attack which met with complete success. Control of interception, including D/F, was left to Kenworthy and Lambert, and their successful effort to locate a room in a house in a terrace in a suburb of London was perhaps the earliest example of this type of work, and proved in the early days the value of co-operation between interception, T/A and cryptography.

I can imagine that there was a considerable amount of clandestine wireless from 1935 onwards, during the Abyssinian and Spanish wars, and various episodes of Hitler’s aggression, but lack of technical facilities prevented any attempt at interception.

One other clandestine network was observed and studied by us in the prewar days, namely that organised by the German Foreign Office. As we were aware that already our own Foreign Office and SIS were taking steps to ensure communications with our embassies and posts abroad in the event of a breakdown of the normal routes, we were not surprised when Denmark Hill in 1937 and 1938 obtained obvious German diplomatic traffic broadcast from an unlisted station in Germany to unknown recipient call-signs as well as obvious replies from unknown stations.

As previously stated, we could not read the traffic, but it could not be mistaken: it was not disguised. Interception, T/A and direction finding enabled us, even in those days, to be certain that every German embassy and legation and many German consulates were equipped with W/T gear for reception and transmission. Denmark Hill was able to make preliminary studies of all the methods of changing frequencies, call-signs, etc, used to disguise as far as possible the originators and the services, so as to avoid interception and identification. When later during the war it became necessary to obtain all this material, these early studies by Denmark Hill proved of very great help.

5. Services

GC&CS, as an office, had no means of obtaining W/T traffic. Admiralty and War Office had set up a large number of intercepting stations during the war, from which DNI (Admiral Sinclair) persuaded the Signal Department to retain two, Scarborough and Pembroke, and the Military Directorate in the War Office to retain one at Chatham. Naturally the first duty of these stations was to watch the service traffic of other powers, but they also undertook to spend part of their time watching the big commercial transmitters in foreign countries with a view to obtaining such government cypher traffic as they heard. I propose to go more fully into this question in section D. But it had to be mentioned here as one reason for the creation of a Naval Section.

Admiralty. The beginning of the Naval Section is obscure in my memory. Clarke, who became the head of the section, did not join until 1921 as he was engaged in writing up the naval history of the Great War. But the Admiralty did lend certain officers, first German, then Italian linguists. There was of course very little German naval material in the early years: there was no German navy to speak of. There was a small amount, but it was soon apparent that we could not read it. The Armistice Commission and the Peace Treaty had made no demands. So far as I remember we concluded that a machine recypher had been applied to the 4-letter code book with which the German navy finished the war, but at that time we knew nothing of the German development of the Enigma machine. It is possible that in 1923-25 they were already using it.

In any case there was no navy, and consequently little traffic, and so interception was dropped.

The Italian navy was also watched, and here we were lucky. There was a navy and consequently a fair amount of traffic, and in early days we did reconstruct the main naval code book because of the delightful Italian habit of encyphering long political leaders from the daily press. As can be imagined in those years and with such habits, the Intelligence value of the effort was slight, but we did build a foundation which proved of value from 1934 onwards.

But even in the early twenties the Admiralty did evince an interest in Japan. But GC&CS only obtained diplomatic and attaché material - no Japanese naval traffic could be intercepted in this country. We knew the Japanese cryptographic methods to be low-grade - the language was the difficulty and linguists were hard to find. The Admiralty, however, had a certain number of interpreters, some of whom were for one reason or another no longer essential for active service. From 1922 onwards we had always one naval officer working in the Japanese Section, reading the diplomatic and naval attaché telegrams. By 1925 we even had officers still on the active list and a scheme was arranged whereby such came to us for two years and then joined the China Squadron in a ship where there were facilities for local interception. Thus a first start was made on Japanese naval traffic.

From then onwards there was a flow of traffic by bag to London where the various codes were segregated and broken as far as possible, and a return flow of officers with skeleton books to carry on the work locally. I believe that by 1930 they were able to be of definite use to the C-in-C, China. Finally the Admiralty sent out Captain Tail (then DDNI) to study the Far East question, and in consequence of his report, set up a small bureau for interception and cryptography at Hongkong (moved to Singapore in September 1939) where Captain Shaw, now retired, headed the first party to exploit Japanese naval signals, to which was added the beginning of Japanese military. The Diplomatic Section had followed the diplomatic and attaché developments, including the introduction of mechanical devices, successfully, and thus it can be maintained that in early 1939, GC&CS had full control of diplomatic and attaché traffic, were reasonably fluent in their reading of all the main naval cyphers and knew quite a lot about Japanese army cyphers as used in China.

To revert to European affairs, the period of dull slackness of naval affairs and traffic, noted in the opening paragraphs of this section, continued with slight alarms and excursions consequent upon naval reviews and visits until around about 1934, when the Italian governments probably began to plan the Abyssinian Campaign. From then onwards, Italian naval traffic was obtained in increasing quantity with increased security measures. The section kept pace with it all, though by 1935 increased numbers and more room had to be provided. Throughout the campaign and in the tenser moments aroused by the threat of sanctions, the section was able to keep DNI fully informed of the strength and activities of the Italian navy. When in the Spanish war the Italians, not content with their own reasonably secure hand methods, introduced the commercial Enigma machine for all their secret naval communications, this proved a heaven-sent opportunity for us to explore machine encypherment. Knox led the party and younger men, such as Bodsworth and Twinn, had their first experience with him, a fact which proved invaluable after 1939.

It was not until the summer of 1936 that any interest was taken in the German navy. But when they appeared that year in the Mediterranean, all our stations were inundated with frequent repetitions of their naval broadcasts. Work began at once under Knox and by this time we were quite aware that the Enigma machine, with the special attachment known as the ‘Stecker’, was the basis of their service signals. Strong efforts were also made by our naval stations to supplement the broadcasts by ship signals and local coast stations in Germany to try to find lower grade traffic. Lack of gear and men prevented this. Knox made considerable progress in his diagnosis until April 1937, when the Germans introduced the new method of indication [4 bigrams] to which he had to admit defeat. Captures in the spring of 1940 showed the correctness of this diagnosis. In 1937 we had no access to mechanical devices which alone enabled this system of indication to be overcome.

But correct diagnosis does not read messages, so the German naval signals were submitted to another process which we called W/T from which we hoped to learn something of German naval activities. Even in the Great War during 1917 and 1918, when new books were introduced and the cryptographers of 40 OB were not in production, the ‘plotting’ section, with the unread signals before them, did continue to produce daily a reasonably accurate situation report. But no German naval signals had been read for 20 years, and it was hardly to be hoped that the Nazi German navy had preserved the habits and routines of the imperial navy. Nevertheless, from 1937 onwards, such an effort was made by officers lent to GC&CS by the Admiralty, reinforced by available members of GC&CS. We had no accurate checks by the cyphers becoming legible; but out of this effort grew the art now called, I think, T/A, which from 1940 onwards has proved a most valuable adjunct to cryptography, quite capable of acting as a trustworthy substitute when the cryptographer is temporarily unproductive.

To sum up the situation of the Naval Section in 1939, including the Japanese branch in Hongkong: they exercised a very fair measure of control of all Italian and Japanese naval cyphers; they had only seen German signals by the Enigma machine and this they could not read; they had started an intensive professional study of raw German traffic with a view to extracting any available intelligence.

Military. Unlike the NID, MI 1 always maintained a personal interest, not only in interception and result but also in cryptography. Before there was any question of a Military Section, officers were sent to us with the definite object of training, while the Admiralty lent officers to assist us in producing results. As stated above, the War Office had, during the war, maintained posts abroad, and early in the twenties decided to set up a permanent intercepting station in the Middle East, and about 1923 Sarafand in Palestine was selected and started to function. In addition to interception, they also intended to read the traffic which affected the area. Therefore at Sarafand Arabic was a primary concern, while French and later Italian were also exploited. I visited there in 1925 and am glad to think that the liaison between GC&CS and Sarafand has been maintained for 20 years. Many army officers worked in both places. MI 1 was also our liaison with a bureau which the Indian army had founded during the war to handle the problems (Persian, Afghan, Russian) which affected India.

Throughout the twenties the military officers who joined us went to sections where their language was used or in which the War Office was interested, because there was no purely military traffic. But very early in the thirties the War Office decided to regularise this somewhat haphazard form of training, and the Military Section was formed to which all army officers with us were attached. Tiltman was made the head of the section, receiving the position of senior assistant on the War Office civil establishment. Members of the Military Section conformed to the routine and discipline of the GC&CS, but MI 1 had the right to dictate their requirements as to training and type of work. At a later date the War Office also recruited civilians on the same lines as GC&CS. Thus was laid the foundation of the very large Military Wing of the war period. Originally the Military Section took over certain of the normal commitments of GC&CS, but with the increasing threat of war, gradually the subject and the traffic on which the sections worked became more definitely military. The Far East began to send back bags of Japanese military material, the Japanese military attachés in Europe began to assume importance. Then the Abyssinian and Spanish wars produced large quantities of Italian military material. All of this latter was tackled successfully, and consequently the section became well trained to face their operational task in 1940.

Naturally the Military Section worked in close co-operation with the military intercepting station at Chatham, and it was thanks to this that the section, and GC&CS as a whole, had, in 1937, their first glimpse of German army and air force material, and of German police transmissions. Knox failed in his effort on the naval enigma, led the team which started to investigate this new problem. Tiltman, deep in other problems, broke in to contribute one vital link. An ever closer liaison with the French, and through them with the Poles, stimulated the attack. Fresh ideas flowed, even from those selected from a university as recruits in the event of war. I think it may be rightly held that this effort of 1938 and 1939 enabled the party at B/P to read the current traffic of the GAF within five months of the outbreak of war.

RAF Section The Air Ministry had, since 1922, contributed to our need for traffic by maintaining a very good intercepting station at Waddington. There was no real air traffic, so we profited. As the Intelligence Division of the Air Ministry was never so politically minded as in the other two services, our diplomatic result could not have had the same value to them.

Our debt to them was therefore the larger. But with the threat of war, about 1935 the Air Ministry decided to form an Air Section to work in GC&CS on the lines of the Military Section. They had no trained experts of their own. They asked, therefore, to have a member of GC&CS transferred to their civil establishment. So Cooper became the first head of the RAF Section and I am sure that the Air Ministry will agree that GC&CS repaid their earlier debt to the full, and with interest. In 1938 further civilians were recruited direct into the section.

From then onwards, Cheadle, whither Waddington had transferred, began to look out for foreign air traffic.

The war in Spain and aggression in Europe gave them ample scope. Italians, Spanish and German operational air-to-ground was collected and worked on with success. So the section had first-hand knowledge of some of the methods used by the Germans when war began.

6 Commercial

For 20 years, during which cable companies submitted all their traffic to the GC&CS, a vast number of telegrams of a purely commercial nature were seen but never copied. Similarly, the operators at the intercepting stations had to hear and pass over far more than they recorded. We only worked on foreign government traffic. Once or twice perhaps we may have looked out for individuals. Once most certainly we did investigate the telegrams of certain oil companies. But this was not our function. In those days of peace, all companies of any repute had their private codes or at least private encypherments of standard commercial codes. Apart from secrecy, it is cheaper to use code for telegrams. The majority of these commercial codes can be purchased in the open market, whatever their nationality. Therefore the reading of such telegrams presents no difficulty, and where encyphered, GC&CS should be able to break it down.

But with the few exceptions noted above, commercial work was not in our mandate and we had not the necessary staff.

Sometime in 1938 the Admiral and the newly appointed DNI formed that opinion that in the events of a troublous political situation in the Far East, the Japanese might take steps to render their diplomatic and service material illegible, and that the communications of the big Japanese firms, particularly as to shipping, might be the only available source of intelligence.

Further, Major Desmond Morton had now organised a section known as IIC for the study of commercial and financial intelligence out of which grew MEW in the latter half of 1939. He was on our circulating list and was always anxious to extend the bases of his intelligence.

Therefore, in 1938, Hope started a very small section to investigate commercial traffic, more especially the telegrams of the big Japanese firms. A library of all the known commercial codes in various languages was assembled as a necessary foundation. But his task was definitely cryptographic.

About this time the Cable Censorship were engaged in drafting their final plans. They naturally intended to stop the use of code for all terminal traffic (except of course for neutral and allied governments whose representatives enjoy cipher privilege). Consequently the Censors themselves would circulate the intelligence derived from terminal plain language. But they did not propose to interfere with traffic transit at censorship points, and they agreed to provide our commercial section with all the commercial code telegrams of this nature. Our intercepting stations were now, in late 1938, asked to record commercial traffic where possible, and as much of this was taken on high speed automatic gear, our slipreading party had even then to be reinforced. The Commercial Section did have 12 months’ experience of a variety of the codes used by all nations, including Japanese, and of the type and mass of plain language commercial telegrams. Above all they began to learn the very necessary discriminations. Never more than 10 per cent of the very large numbers of telegrams received really justified translation and circulation and the accurate selection of this 16 per cent required training and close liaison with the users.

 

V

SUPPLEMENT: TRAFFIC

The Cabinet authority establishing GC&CS gave no directive as to raw material, without which little could be done. But the authorities controlling the new body were fully alive to the necessity and supported to the best of their power all suggestions we put forward. We only had the experience of four years of war, when such a question was simple, because our results were valued.

Full cable censorship provided copies of all cable traffic. The development of the scientific methods of intercepting W/T traffic, service or commercial, dated only from 1914 but was now practised on a considerable scale by stations controlled by Admiralty, War Office and GPO. It was necessary to ensure that the provision both of cable and W/T traffic should continue under peace conditions.

1. Cables

The conclusion of the Treaty meant the suspension of censorship. Temporary unofficial arrangements were made with the moribund censors which provided the cable traffic for some further months. But legislation in the form of the Official Secrets Act gave the government the right to obtain cable traffic for scrutiny purposes not for censorship. A clause was inserted authorising a secretary of state to issue a warrant to cable companies operating in the UK requiring these companies to hand over all traffic passing over their systems in the UK within ten days of receipt or despatch to a named department, for the purpose of scrutiny, the secretary of state alleging that a general state of unrest and world emergency required him to make this demand.

I believe the Secretary of State for Home Affairs signed the original warrant and named the Admiralty. I believe occasional questions were asked in the House but we continued to receive all cable traffic from all the companies until September 1939, when cable censorship was again instituted, and once again the Censors provided us through the war with copies of the traffic we asked for.

Throughout the 20 years (1919-39) it was our aim to make this procedure work smoothly with the companies (British and foreign). It was undoubtedly a nuisance for them to have to send all their traffic in sacks to an outside department, and I have always considered that the credit for smooth working and no questioning should go to Maine. To carry out the work of sorting and copying we took over a comparatively small body of GPO lower grade staff who were accustomed to this work. Our aim was to inconvenience the companies as little as possible, and throughout we tried to let them have their traffic back within 24 hours. We only had to sort out and copy government traffic and occasional suspicious characters in whom our security authorities were interested. I believe we never failed to return all the traffic, though many million telegrams must have passed through our hands.

Another very valuable job carried out by Maine was to obtain traffic from stations abroad where, during the war, there had been a censorship point, e.g. Malta, Hongkong, Bermuda. Traffic at these points was not required under the warrant.

Malta, above all, the focal point for traffic between Europe and all the East, was of the highest importance. Maine was able to arrange with Messrs Cable and Wireless, who operated the stations, that they should have all the slip transmitting Malta sent back by bag to London, ostensibly for accountancy purposes. We received it, engaged slipreaders, and had this valuable material read regularly, though of course with a considerable delay. For instance, the Japanese traffic to France and Germany always went via Malta. All Italian cable traffic passed there. Thus we were, throughout, enabled to watch the growth of the Axis combination.

In a similar way we were able to watch other old censorship points and, finding the traffic of little value, to give them up again.

It is probable that once again after this war, Malta traffic will be essential.

Also, with the CTO, Maine’s excellent liaison proved of the greatest help at times when foreign embassies during big conferences requested and obtained private lines from their embassy to their capital. The Germans, the French and other great powers adopted this procedure on occasions. Of course these private lines had to pass through the CTO, and Maine was always able to arrange for measures to be taken there whereby copies became available to us.

Finally, when the state of unrest in the world became intense, from 1935 onwards, it was found that the 10 days’ delay granted by the warrant became intolerable. Maine was able to cut it down to 24-48 hours in the case of foreign companies, and to instant service, where necessary, in the case of the CTO and Cable and Wireless.

Between us and the companies there has never been any question as to why we wanted the traffic and what we did with it. The warrant merely said scrutiny, and the traffic arrived back apparently untouched within a few hours. I have no doubt that the managers and senior officials must have guessed the true answer, but I have never heard of any indiscretions through all these years with so many people involved.

In short, barring the delay, we always had as good service of cables when we dealt direct with the companies as in the periods of censorship.

2. W/T

We started the peace regime with two Admiralty stations, Pembroke and Scarborough, gradually decreasing their naval work owing to absence of targets and increasing their watch of the big foreign commercial stations, and thereby producing foreign government cipher traffic, and (in the early days) a good deal of foreign government P/L, especially from Moscow.

Our director was at that time the DNI, Admiral Sinclair, who was obviously able to obtain the willing assistance of the Signal Department who owned the stations and the gear, and of ACR who provided the operators. Further, a Cabinet committee for postwar planning with General Romer as chairman had apparently planned for further interception and had appointed Admiral Sinclair as Co-ordinator of W/T interception. Before the Admiral left (in 1921) to take up the post of OC Submarines, naval interception by these stations was on a firm, if modest, footing, complicated only by the fact that ACR controlled the staff, DSD was responsible for station and sets, and DNI had to indicate the programme of work.

About this time (1921) the WO also set up a station at Chatham under MI IB, who were also prepared to produce material for us. The GSO2 or 3 of MI IB became a liaison officer to GC&CS, and we worked out a plan of interception with him. Later (about 1923,1 think) the Air Ministry joined up also and founded a station at Waddington under AII, who also nominated a liaison officer to us. So, when the Admiral returned in 1924 as Director, there did exist a means of co-ordination on a low level, that is, such sets and operators as existed were used to our best advantage but any expansion was out of the question. He resumed his function as Chairman of the Co-ordinating Committee and held an annual meeting of the Directors of Intelligence at which on each occasion the Head of GC&CS and the liaison officers assisted. At the early meetings little could be done beyond allotting priorities of work as still no expansion could be hoped for.

One of the first major actions the Admiral undertook was to arrange with the Police Commissioner for the loan of a small body of constables whom the Commissioner had used as a police W/T unit, I think, for interception of illicit transmissions in this country and for control of the police W/T network in London. These constables (10 to 12) had a small station at Denmark Hill, where their work was directed by a civilian engineer on the staff of the Receiver, Kenworthy by name. The Admiral undertook to pay for these men and the upkeep of the station while the Commissioner agreed to ask no questions about their work. This was the first station which undertook purely diplomatic work over which GC&CS had full control. It was soon apparent that Kenworthy possessed a flair for this work which amounted to genius. To him the FO and the Service intercepting authorities owe a very great debt, not only as a technical W/T engineer designing and constructing suitable gear, but also as the instructor in the matter of interception of difficult transmissions, and as a pioneer in the interception of non-Morse transmissions.

About 1929 the Admiralty began to take the Far East situation more seriously. The Committee of Co-ordination was able, not only to advise, but also to use the prestige of its members to force necessary expansion through the various departments. The Committee became known as the ‘Y’ Committee, and they formed a ‘Y Sub-Committee’, consisting of the head of GC&CS and the liaison officers. This sub-committee from then onwards met once a fortnight in the GC&CS. Its terms of reference were: to study the work of the various stations, to co-ordinate the programmes allotted, to avoid waste of effort and to investigate new lines of traffic and new means of transmission. Thus policy and expansion were the functions of the ‘Y’ Committee, while the sub-committee formed the executive, each member reporting if need be, to his own director.

This continued smoothly until about 1935. Certain other departments were asked to appoint liaison officers who sat on the sub-committee, notably the GPO with whom we had hitherto little contact, the chairman of the W/T board, and later Gambier Parry (then Captain) who had been appointed as Section VIII of SIS.

From the beginning of the Abyssinian war the sub-committee began to take a far more active part, and co-ordination of programmes became a more difficult problem, because there was now service material to be intercepted and new service sections to study the traffic. Consequently, fewer sets were now available for diplomatic traffic at a time when the contents were of more vital interest.

With the best will in the world, the service officers could hardly make a case for expansion on behalf of diplomatic traffic. It was possible for the Admiral to persuade the Commissioner to increase the staff at Denmark Hill, but with the increase of world unrest, it became clear that the FO would have to take its share in interception. Protracted negotiations resulted in success, but it was not until 11 September 1939 that the first station was opened at Sandridge. It had been planned and erected by the GPO. All the gear was designed and provided by the GPO engineering branch and the operators were all GPO staff. The FO footed the bill and GC&CS directed the various programmes of work. This very important development was one of the major actions of the sub-committee.

Another was the introduction of teleprinter links between the stations and GC&CS. Hitherto all traffic arrived by registered post creating an average delay of twelve hours. During the anxious days of the Spanish war it had become obvious that all delays must be cut down, and the service members were able to use the value of the results to induce their authorities to sanction the installation of the T/P links between GC&CS and the naval stations (Flowerdown and Scarborough), the WO station (Chatham) and the RAF station (Cheadle). Of course, not only service material but also diplomatic was passed over these links. Thus we had two years’ experience of rapid and efficient communication.

In the spring of 1938 the Admiral bought the property at Bletchley Park, and the GPO set to work to equip it with suitable lines of communications. In the autumn of that year the service sections of GC&CS spent a month at the Park simulating, as far as possible, wartime conditions and direct communication. Thus it fell out that our work could definitely begin on 1 August 1939, when the Admiral ordered the service sections to take up their war stations. The diplomatic and commercial sections were ordered to move on 15 August.

From then onwards the university recruits began to join, so that by 1 September when war was declared, GC&CS was in action at its war station, already in process of growth towards that vast and successful body whose full story will perhaps never be told.

2 December 1944