GCHQ

Critical to the breaking of Enigma was assistance from the secret services of France and Poland. French intelligence employed a lugubrious German agent called Hans Schmidt, who worked in the German military cypher department. Fond of the finer things in life, which the French secret service supplied to him in abundance, Schmidt divulged many technical documents about Enigma, including messages in both clear and encyphered text. He was later betrayed, and would commit suicide using cyanide procured for him by his daughter. By 1938 these secrets were being shared with the British through ‘Biffy’ Dunderdale, the SIS station chief in Paris. However, when the French gave the British material on German Air Force communications a further secret was accidentally revealed, namely that the French were also working on Enigma in collaboration with the Poles. In January 1939 Alastair Denniston took two of his top code-breakers, Hugh Foss and Dilly Knox, to Paris to meet their French and Polish opposite numbers. Eventually they discovered that the Poles had completely reconstructed the German version of the Enigma machine.17

Remarkably, by 1938 the Polish code-breakers were able to read the majority of German Army Enigma messages. The Polish breakthrough had been to train professional mathematicians to help them, together with the use of a primitive processor called the ‘bomba’ or ‘bombe’ – so named because of the alarming ticking noise it made – to find the rotor settings. One of their first ‘bombes’ was a weird contraption that consisted of no fewer than six Enigma-type machines wired together to provide rapid processing of possible solutions. Polish resources were limited, and by late 1938 new advances in the Enigma machine were running ahead of the ability of the Poles to do their calculations. But the precious secrets that the Poles taught the British were enough to continue the unravelling of Enigma. The timing was an extraordinary stroke of luck, since the talented Polish cypher bureau was within two months of being broken up by the coordinated German–Soviet invasion of Poland in the autumn of 1939. Before the Polish secret service was forced to flee Warsaw, its agents had achieved the remarkable feat of stealing several examples of the military Enigma machine from the German factory where they were made.

In the late 1930s, Britain lived in the shadow of the aerial bomber. Following the tragic fate of the Spanish town of Guernica in the spring of 1937, the presumption was that the first few days of the approaching war with Germany would bring untold destruction from the air, levelling the cities of Europe. By the Munich Crisis of 1938, Whitehall had begun to make emergency preparations. Admiral Hugh Sinclair, the Chief of SIS, was busy looking for alternative wartime accommodation away from London for both SIS and GC&CS. He soon settled on a country house, Bletchley Park, near Milton Keynes in Buckinghamshire, as an ideal location for the code-breakers. Much has been made of Bletchley Park’s proximity to Oxford and Cambridge, but in fact the availability of good trunk cable communications was the dominant consideration. Bureaucratic bickering now erupted. Although GC&CS was run by the Foreign Office, its relocation was considered to be war contingency planning, so the diplomats insisted that the military pay the bill. Predictably, the War Office insisted that GC&CS was nothing to do with it, and emergency relocation for Britain’s most valuable wartime asset stalled. In the end, Hugh Sinclair bought Bletchley Park with his own money, paying over £7,500 (more than £330,000 at today’s prices). This remarkable act of generosity allowed the first wave of evacuated staff to arrive at Bletchley on 15 August 1939. Sinclair’s largesse did not stop there. He acquired a top chef from London to provide food to the code-breakers in a restaurant in the main hall, complete with full waitress service.18

The emphasis at Bletchley Park was distinctly military. The main body of GC&CS was initially broken up into Naval, Military and Air Sections and allocated to the ground floor of the main house, while SIS was given the top floor, indicating that it still ruled the roost. On the periphery, an ever-growing collection of numbered wooden huts – including the famous Hut Three and Hut Six – were being constructed. Particular activities were associated with each hut: typically, the core of the Enigma problem was worked on in Hut Six, while its exploitation for intelligence purposes was undertaken in Hut Three. One former code-breaker recalls that the main house was soon ‘too small for more than a handful of top brass and their immediate acolytes’. So Bletchley Park’s considerable garden, with its rosebeds and delightful maze, gradually disappeared beneath the expanding penumbra of temporary structures.19 The shadow of the bomber even reached out to Bletchley Park. The radio transmission infrastructure involved elaborate aerials which had the potential to give away the site’s location from the air. Accordingly, Bletchley Park’s own radio station was moved to nearby Whaddon Hall. As the operation gained momentum, other nearby premises were absorbed. Elmers School, a neighbouring boys’ boarding establishment, was requisitioned for the GC&CS Diplomatic Sections.

Bletchley Park was Admiral Sir Hugh Sinclair’s last bequest to Britain’s sigint community. Through the early autumn of 1939 it was clear that he was terminally ill with cancer. His deputy and heir apparent, Stewart Menzies, was not regarded as a great brain, and indeed despised intellectuals. Sir Alexander Cadogan, the Permanent Under-Secretary at the Foreign Office, vigorously resisted the idea that Menzies might succeed Sinclair, and argued for someone from outside SIS to shake the organisation up. Senior SIS officers, however, did not want ‘a new broom at this critical stage’.20 Cadogan noted in his diary, ‘I am not satisfied that Menzies is the man,’ but Menzies did have a crude talent for furthering his own ambitions, which he soon demonstrated. On Sunday, 5 November he came to see Cadogan bearing the sad news of the death of Sinclair the previous day. Cadogan noted that he ‘gave me a sealed letter from “C” recommending him (M[enzies]) as successor’.21 Lord Halifax, the Foreign Secretary, pressed for Menzies, who was finally accepted as the new Chief on 28 November.22

The arrival of Menzies was a problem for Bletchley Park because the code-breakers were still subordinate to SIS. Under Menzies the administration of SIS was ‘chaotic’, and its headquarters was in ‘a state of upheaval’ throughout 1940.23 Cadogan maintained his view that Menzies was a mentally disorganised intriguer who devoted more time to protecting the interests of SIS than to serious intelligence-collection. Typically, in March 1941, after Cadogan had met Menzies and the Directors of Intelligence of the three armed services, he recorded in his diary: ‘“C” as usual, a bad advocate on his own behalf. He babbles and wanders, and gives the impression he is putting up a smokescreen of words and trying to put his questioners off the track.’24 Cadogan longed to see a thorough overhaul of SIS, which he regarded as an organisational basket-case. However, as the war dragged on, he had less and less time for the politics of intelligence.25 Quite understandably, SIS wanted to keep all code-breaking under its wing, since it was a form of foreign intelligence-gathering. Menzies was also adamant that he should retain personal control over Ultra.26 If possible, he preferred to take this material to Churchill personally, basking in its reflected glory. But he did not know how to manage Bletchley Park, and as a result it was under-resourced.27 In the words of one SIS contemporary, Menzies regarded anything to do with personnel or administration as ‘dirty work’, and would go to considerable lengths to avoid it.28

Bletchley Park may have been chaotic, but it was a creative and innovative chaos that allowed the code-breakers to make a fresh start in the Buckinghamshire countryside.29 The head of GC&CS, Alastair Denniston, spent the autumn of 1939 making detailed war preparations. His task was to find new cryptographers to fill out the ranks of Bletchley Park. His valuable contacts with the Poles and their success with the ‘bombe’ had led him to realise that he not only needed more code-breakers, he also needed mathematically-inclined individuals. Most of the current inhabitants of GC&CS were linguists with a penchant for Latin and Greek. He now needed people who loved maths and machines, and in September 1939 he was actively scouring the high tables of Oxbridge colleges for talent. The brilliant new mathematicians he recruited included Gordon Welchman from Trinity College, Cambridge, who would run the heart of the code-breaking operations in Hut Six. He brought with him Stuart Milner-Barry from the same college, who was the chess correspondent of The Times and who eventually took over as head of Hut Six. In turn, Milner-Barry brought fellow members of the British chess team, Hugh Alexander and Harry Golombek, to Bletchley.30

These arrivals came not a moment too soon. Hitler’s attack on Poland had tipped Europe into all-out conflict, and Bletchley Park was now a fully operational war station. The pressure was on to make progress against Enigma. The most brilliant mind engaged in this task was Alan Mathison Turing, who made an early and important contribution. Despite understanding the abstract problems of Enigma some months into the war, GC&CS was having difficulty in breaking any real Enigma messages, and was not delivering much product. To have examples of the machine was not enough, since the security of the messages it sent depended on the ‘key’, in other words the settings of the machine, which changed each day. Turing was sent to see the remnants of the Polish code-breaking team, now residing near Paris, to try to work out what the British were doing wrong. The Poles explained that the British had failed to think through the way in which the wiring was attached to the rotors of the Enigma machine.

In early 1940, with this further helpful shove from its allies, Bletchley Park began breaking substantial amounts of Enigma traffic. There were many different Enigma cyphers, and to distinguish them, they were colour-coded. In February 1940, Bletchley Park began breaking ‘Red’, which was an invaluable system used for liaison between the German Army and the Luftwaffe. Periodically, a change to a German cypher system would cause the British code-breakers to lose it for a while, and quite often recovering it depended on second-guessing the lazy habits of the operators. German overconfidence in the improved Enigma machine led to basic mistakes that greatly simplified the task of those whose objective was to tease out the rotor setting for each day.31

By early 1941, the flow of material from the breaking of Enigma was impressive. The intelligence from Bletchley Park was circulated on a very select basis, and was marked with the code word ‘Ultra’ to denote the extremely high level of security attached to the material. Menzies showcased his triumph by taking senior figures from Whitehall on day trips to Bletchley Park. On 11 January it was the turn of Alexander Cadogan. He noted in his diary:

Cold but thawing. Had a rush at the FO till 11, when I left with Menzies for Bletchley. Got there about 12.30. Very Interesting – I should like to spend a week there so as to try and understand it. A charming young Cambridge professor of geometry – Welshman [Gordon Welchman] – did his best with me. A good show, I think.32

Others soon made the pilgrimage to the strange mock-Tudor mansion surrounded by temporary huts. On 6 September 1941 Winston Churchill himself, now Prime Minister, stood on a pile of bricks left by some workmen alongside Hut Six and gave an impromptu speech – delivered with deep emotion – about the value of Bletchley Park to the war effort.33

Unbeknown to Churchill, Bletchley Park was in deep crisis. This was partly due to its rapid growth, and partly to the uncertain institutional boundaries that were evolving almost daily. The situation was exacerbated by a complex relationship with the ‘Y services’, the lower-order radio intercept organisations run by the Army, Navy and Air Force that fed Bletchley with captured traffic. Meanwhile the three armed services were themselves vying for increased control over who received the output from GC&CS. This was precisely the kind of complex organisational puzzle that Menzies was ill-equipped to deal with. Matters reached a head in the autumn of 1941, forcing Menzies to appoint a Joint Committee of Control, which included members of both SIS and GC&CS. However, as the historian Philip Davies observes, ‘Like so many of Menzies’ administrative initiatives, the committee proved unequal to the task.’34 There was also a general resources problem. Having made significant inroads into German Enigma traffic, there were simply not enough staff at Bletchley Park to process the vast torrents of accessible German communications. Neither Alastair Denniston nor his deputy, Edward Travis, had the pull in Whitehall to overcome the shortage.35

Churchill was not ignorant of this state of affairs for long. Recalling the Prime Minister’s kind words during his recent visit, the code-breakers resolved to go straight to the top. On 21 October 1941, four of the most brilliant minds at Bletchley Park, Hugh Alexander, Stuart Milner-Barry, Alan Turing and Gordon Welchman, wrote directly to Churchill to beg for more resources, explaining that their work was so secret that it was hard to explain their requirements to those who controlled personnel.36 So secret was their missive that Milner-Barry took the train to London and delivered it personally to 10 Downing Street. Churchill was shocked by these revelations, and demanded ‘Action This Day’. He ordered his military assistant, General Hastings ‘Pug’ Ismay, to ensure that GC&CS had everything it needed, and to report that this had been done.37 As a result, Bletchley Park underwent a further expansion, and more importantly a major reorganisation.38

GC&CS was now divided into two distinct parts, civil and military. The end of the Blitz meant that the civil side, which dealt with economic and diplomatic traffic, could be sent back to London with relative safety. It took up residence in Berkeley Street, partly because the work of attacking diplomatic codes often had to be coordinated with discreet telephone taps on the foreign embassies in London. The military side remained at Bletchley Park. This did not resolve the heated arguments about who controlled the spoils of GC&CS, but it did address the immediate accommodation problems, and created two organisations of a more manageable size. Menzies retained his post as overall Director, but was a notably absentee landlord. Alastair Denniston was sent to London as Deputy Director (Civil), while his talented deputy, Commander Edward Travis, remained at Bletchley as Deputy Director (Services).39 Travis was now the rising star.40

British code-breaking in the early years of the war was not just about the German military secrets revealed through Enigma. Even harder to break than the Enigma machine had been a German teleprinter on-line cypher machine known as ‘Tunny’, used by the German High Command to produce ‘Fish’ messages. On-line cypher machines were especially challenging because they were automatic, and sent a continuous stream of text, much of it dummy material, sometimes offering no obvious start or end points to each message. This went some way to eliminating another weakness of the Enigma machine – its operators, who were prone to human error. To address the problem of ‘Tunny’, the British later built ‘Colossus’, one of the earliest general-purpose electronic machines, and perhaps the first device that might be described as a ‘computer’. Conceived by Professor Max Newman and then developed by Tommy Flowers from the British Post Office research facility at Dollis Hill, this was one of the supreme technical achievements of the war.41

The achievements of the civil side of GC&CS have often been neglected. By 1940 it was analysing not only the diplomatic codes and cyphers of the Axis powers, but also those of more than twenty other countries. These included the Soviet Union, which did not enter the war until it was attacked by Germany on 22 June 1941. The diplomatic communications of quarrelsome allies such as the Free French, or important neutrals such as the Turks and the Spanish, proved as interesting and as useful as those of Germany. Moreover, the traffic of Germany’s allies, such as Japan, could shed a penetrating light on the mindset of Berlin. Throughout 1941 Hitler held regular meetings with Baron Oshima, the Japanese Ambassador in Berlin, often referred to as ‘Hitler’s Japanese confidant’. Japan had its own complex cypher, known as ‘Magic’, produced by a machine called ‘Purple’, and Oshima used it to send detailed accounts of his long conversations with Hitler to Tokyo. ‘Magic’ had been broken by the Americans, and early Anglo–American cooperation on code-breaking ensured that all this was being read in London. Remarkably, Berkeley Street was also working on the cyphers of the United States, which did not join the war until the Japanese attack on Pearl Harbor on 7 December 1941.42

The dramatic events of 1941 transformed the course of the Second World War. Although the Battle of Britain had staved off the possibility of a German invasion, by the summer of 1941 Britain had been fighting for almost two years without a major victory. Therefore, Hitler’s bizarre decision to invade Russia in June 1941, which required the legions of the Wehrmacht to turn east, provided a welcome breathing space. After Japan’s attack on Pearl Harbor, Britain, the United States and Russia found themselves ranged together against the Axis in what was soon called the ‘Grand Alliance’. Welcome as this was, a genuine world war created new dilemmas for the denizens of Bletchley Park, who now confronted the ticklish issue of large-scale Allied cooperation in the business of code-breaking.

2 Friends and Allies

…there is no better analogy than the schoolboy with his stamp collection.

GC&CS, discussing intelligence cooperation with the Russians in 19431

The most secret aspect of Bletchley Park’s wartime work was its dealings with friends and allies. Many have pondered whether the British attacked Soviet codes and cyphers during the Second World War. The official history of British intelligence insists that Churchill ordered this activity to stop in June 1941, following Hitler’s invasion of the Soviet Union, since Moscow had suddenly become an ally.2 However, it is now clear that this is quite untrue. At the end of October 1941, intelligence chiefs were actually discussing the expansion of the sigint organisation in India, which was then dealing with ‘material from Russian, Persian and Afghan sources’. Remarkably, it was not yet working on German traffic.3 Moreover, in January 1942, and again in early 1943, the British and the Americans were discussing the mutual exchange of intercepted material from ‘Slavic nations’.4 Soviet cyphers had been the core business for Britain’s interwar code-breakers, and work on this material never stopped completely during the Second World War.

To understand why, we must cast our minds back to the approach of the war. During the 1930s, GC&CS continued to follow the traffic of the Comintern even after other Soviet systems were lost. This revealed persistent efforts to subvert the British Empire in locations such as India, Malaya and Hong Kong. Indeed, the Soviet Union appeared to be in league with Germany after the Nazi–Soviet Pact of August 1939. It is often forgotten that Poland was invaded by Germany and the Soviet Union together. For a nightmare period between August 1939 and June 1941, many suspected that Germany, Italy, Japan and the Soviet Union would act in uneasy concert, dividing the spoils of the world between them. This was precisely the plan that Germany’s Foreign Minister, Baron Joachim von Ribbentrop, was trying to press upon his irascible master. However, in the end Adolf Hitler’s racist outlook could not tolerate the idea of alliance with the Slavic peoples, and he had always declared his desire for ‘Lebensraum’ in the east.5

Throughout this dangerous period, before Hitler and Stalin turned upon each other, the Soviet Union remained a key intelligence target. SIS even organised a secret squadron to conduct aerial reconnaissance of possible bombing targets deep inside southern Russia, notably the oilfields. GC&CS developed close relations with code-breakers in the Baltic states who were also working on Soviet codes. A month after the outbreak of war with Germany, Clive Loehnis, a naval officer at GC&CS (who would become Director of GCHQ in the 1960s), told Alastair Denniston that additional premises were needed to cope with the increase in the interception of Soviet military traffic, so new buildings were erected at Scarborough.6 With the military chiefs keen to ‘get cracking on Russian traffic’, Denniston began a unique and profitable experiment. In 1939 GC&CS sent a party of British sigint operators to Sweden to work secretly out of the British Embassy in Stockholm, where there was better radio reception from Russia. The creation of this forward listening station was fortuitous, since Stalin embarked on the Winter War against Finland in November 1939, and GC&CS enjoyed a front-seat view of the whole proceedings.7

John Tiltman remained the key figure in the effort against Soviet communications. A colonel in the King’s Own Scottish Borderers, he was noted for his smart uniform, which included tartan trews. However, as the war progressed he came under the influence of the spirit of Bletchley Park, and was often seen in a baggy pullover and green corduroy slacks.8 One of his first duties was to visit Helsinki to conclude a deal with the talented Finnish code-breakers. Britain funded the expansion of the Finnish cryptographic bureau, and supplied it with the latest equipment in return for material on the Soviets. In March 1940, after imposing a series of humiliating defeats on the Soviets, the Finns signed the Moscow Peace Treaty, ceding about a tenth of their territory.9 The sigint deal with the British was unaffected, and indeed in September 1940 its scope was expanded during a visit by Admiral Godfrey, the Director of Naval Intelligence. According to an internal GC&CS history written after the war, ‘The Finns had agreed to supply us with copies of all their intercepts and cryptographic successes, provided that we did the same.’ Preceding the agreement with the Americans by more than a year, this was perhaps Britain’s first comprehensive sigint alliance.10

By March 1940, the interception of Soviet traffic was big business. For the first time, collection began in the Middle East, at Sarafand in Palestine, although it was still sent to India for analysis. Soviet traffic was also being taken at Ismailia in Egypt and Dingli in Malta. Meanwhile, in Hong Kong, other British sigint operators were also listening to the Soviets before they packed up their equipment to move to Singapore in anticipation of a Japanese attack. The surge of Soviet traffic meant changes were required at GC&CS, where an inter-service Soviet section was created to work in close conjunction on naval, military, air, diplomatic and commercial material. After the fall of France in the summer of 1940, evacuated French cryptographers joined the effort on Soviet traffic at GC&CS. A Polish section, based at Stanmore on the northern fringes of London, soon discovered that it was able to listen in to Soviet traffic as far away as Ukraine.11

Ultra had provided Bletchley Park with an intimate picture of the build-up of German forces in the east, prior to their attack on the Soviet Union. As early as January 1941 it was clear that Hitler’s vast armies were being moved eastwards in preparation for some grand project. Yet even with the evidence of many German divisions massing in the east, Whitehall refused to believe that Hitler was mad enough to deliberately opt for war on two fronts. Like Stalin himself, the British Chiefs of Staff believed that this was more likely to be a prelude to a German ultimatum, a bluff in which Hitler would demand the cession of some further territory in Eastern Europe. Throughout early 1941, Stalin believed that all war warnings were self-serving efforts at deception by the West, which sought to provoke a war between Germany and the Soviet Union. Stalin has frequently been ridiculed for ignoring the warning signs of the impending attack, but despite the benefits of Ultra, it was only the month before the fateful date of 22 June 1941 that British intelligence chiefs realised what was about to occur.12