had effectively won the war.[36] Robert Harris, author of the novel Enigma (1995), rightly points out that most of the major combatants had military forces that were superior to those of Britain, not least in their weapons technology. Bletchley Park was the one place where we enjoyed a crucial world lead.[37] Harry Hinsley, a junior figure at Bletchley Park, but later the official historian who produced a magisterial study of intelligence during the Second World War, has famously asserted that Ultra shortened the war by several years, saving countless lives on all sides. Without Ultra, he states, ‘Overlord would have had to be delayed until 1946’.[38] Andreas Hillgruber, the distinguished German historian of Hitler’s strategy agrees, adding that as a result the Soviets might well have advanced much further west.[39]
Yet others, including the British historian Paul Kennedy, have argued that the Second World War was largely a battle of material production, and that once America and Russia were both pitted against the Axis, their industrial might made the outcome only a matter of time – epitomised by the use of the atomic bomb in August 1945. In reality, the debate about the overall value of Bletchley Park has a troubling ‘What if?’ quality. Inevitably, we are encouraged to ponder the alternative universe of ‘no Ultra’. Ralph Bennett, like Harry Hinsley a Bletchley Park veteran turned historian, has expressed impatience with such counter-factual speculations, regarding them as a parlour game. He has argued that the absence of Ultra would have forced the faster development of other forms of intelligence, such as aerial reconnaissance.[40] Peter Calvocoressi, another distinguished historian who spent the war at Bletchley Park, has dismissed Hinsley’s assertions as ‘silly’.[41]
Some propositions can however be advanced with confidence. Ultra and other kinds of sigint contributed hugely to the outcome of the Battle of Britain. The breaking of naval Enigma changed the course of the Battle of the Atlantic, allowing the Admiralty to direct convoys away from concentrations of U-boats and bringing the level of ship losses down to a bearable, although still frightening, level. This in turn allowed a breathing space for more successful anti-submarine warfare techniques to be developed which would finally turn the tide in the battle against the U-boat in 1943. Ultra also contributed greatly to the British naval victories at the Battle of Cape Matapan (March 1941) and the Battle of North Cape (December 1943). Parallel code-breaking work by the Americans in the Pacific allowed the dramatic interception of the aircraft carrying the brilliant Admiral Yamamoto, architect of Pearl Harbor, which sounded the death knell for Japanese naval forces in the Pacific. It is impossible to understand the war at sea without comprehending the contribution of Ultra in the west and the breaking of a range of Japanese cypher systems in the east. Appropriately, it fell to a naval officer, Commander Edward Travis, to pilot Bletchley Park as it sailed forward into the post-war era.
Even in the spring of 1945, final victory in Europe had loomed like the end of an interminable school year – with the distant summer holidays already beckoning. Bletchley Park, with its nearby dormitories and improvised tennis courts, had looked rather like a vast boarding school waiting for the end of term. Post-war worries were not troubling many of the brilliant minds there. Instead, for the most part they were yearning for an end to war and a return to peacetime activities. The majority of Bletchley’s wartime residents were exhausted from years of gruelling hard work. The intellectual pressure had been enormous, and some had suffered nervous breakdowns: Jean Thompson, a Wren who worked at one of the outstations, recalls that they routinely referred to Bletchley Park as the ‘Nut House’.[42] Most code-breakers greeted the end of the war with relief, returning to their former activities in ivy-covered colleges, libraries and museums. However, a minority had been bitten by the intelligence bug. They understood the fundamental importance of what they had been doing for the future of international affairs, and would stay on.
Those who remained at Bletchley Park were also thinking of ‘escape’ – but in a different sense. For them, the end of the war did not so much offer an opportunity of personal freedom, but more the possibility of liberation for the GC&CS. Their remarkable achievements over the last five years suggested that GC&CS might cease to exist under the cloying direction of Britain’s traditional overseas secret service, SIS, where the senior staff were often failed cavalry officers recruited in White’s or Boodle’s. Instead, GC&CS might hope to become an intelligence agency in its own right, perhaps one of a new and different kind. Indeed, its rising status was already signalled by a gradual change in everyday usage from terms like ‘GC&CS’ and ‘BP’ to the rather grander cover name of ‘Government Communications Headquarters’, or ‘GCHQ’, which had been in intermittent use since early 1940.[43]
Bletchley Park had already taken some important strides towards becoming a fully-fledged intelligence service. Peter Calvocoressi, one of its distinguished wartime denizens, recalls that in its pre-war incarnation the Government Code and Cypher School was exactly what its name implied, ‘and no more’. It made up codes for use by the British government, and broke the codes of other nations. But at Bletchley Park, and especially under Gordon Welchman in Hut Six, code-breaking was gradually married to an intelligence process to provide a sophisticated system for sigint exploitation. No less importantly, Bletchley also designed a means for the secure and rapid distribution of sigint to essential customers, even in distant theatres such as South-East Asia. The sheer pressure of wartime exigency forced rapid and logical developments that might otherwise have taken decades.[44]
Another massive achievement was that Bletchley Park and its diplomatic equivalent at Berkeley Street in London were properly ‘integrated’, mixing up staff from the three armed services and civilians. This was immediately obvious to any visitor from the curious blend of uniform and civilian dress, often in exotic combinations. Occasionally a visiting Admiral or General would fulminate to see members of his service dressed in colourful pullovers, and demand that they return to full uniform. However, the top brass on day trips from Whitehall were little more than a temporary nuisance. During the 1940s a sigint service which mixed up civilians and personnel from the armed services was quite remarkable. It would take the Americans until the early 1950s to achieve an integrated organisation that mirrored Bletchley. In Nazi Germany as Calvocoressi recalls, the situation had been even worse, for there ‘six or seven different cryptographic establishments fought each other almost as venomously as they fought the enemy’.[45]
In the social anthropology of intelligence, sigint was emerging as the dominant tribe. ‘The Ultra community at BP saw itself as – perhaps was – an elite within an elite,’ recalled one code-breaker. Material gathered by other kinds of intelligence agencies was merely ‘Top Secret’, but sigint material was compartmentalised as ‘Top Secret-Ultra’. The ability to impose draconian security on its product would be a hallmark of a fully-fledged sigint organisation, and dominated its relations with its friends and allies in the code-breaking world. This security obsession also extended to people. The security rule at Bletchley Park was ‘Once in, never out.’ In other words, once people had worked in sigint, there was a reluctance to allow them to move to other areas of war work, and they were effectively ‘captive’ for the duration of the war.
Dominance was partly about size. By the end of the war, over ten thousand people were labouring under Bletchley’s direction. The expanded bombe effort alone led to the creation of five further outstations as far away as Stanmore and Eastcote on the outskirts of London. Working alongside GC&CS were the listening units of the armed forces, known as the Y services. Although these fed high-grade material to Bletchley Park, they also worked on low-grade material for their own purposes. Often considered ‘poor relations’, they derived their intelligence either from listening in to low-level tactical communications that were not encrypted, including clear voice traffic, or by simply analysing the flow of traffic. Analysing the patterns of radio traffic, including volume and direction, even without breaking the codes, could reveal a great deal of information about the enemy, and GC&CS worked closely with the armed services to develop what were known as the ‘Y stations’. Bill Millward, who continued to serve long after the war, recalls that Bletchley Park’s relationship to the Y services was to become ‘a sort of university of signals intelligence, developing techniques which all might share’.[46] The Y services had been largely responsible for deducing the enemy ‘order of battle’, the structure, strength and location of the units of the German armed forces. The Navy ran intercept sites at Scarborough and Winchester. The Army ran a site at Fort Bridgewoods near