GCHQ. Richard Aldrich

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