May 8, 1945. As crowds in London danced themselves dizzy with jubilation, and as bonfires were lit across the land, celebrations were a little more discreet in one particular corner of Buckinghamshire. That warm evening, on the lawn outside the large Victorian house, young men and women gathered with drinks, the sound of gramophone music gently echoing from within.


The conflict in Europe was over. But for some of these young people, an entirely new kind of war had already begun.

These brilliant youngsters were the code-breakers of Bletchley Park. Their success at breaking into the apparently insoluble Nazi Enigma codes and reading the enemy’s communications had (some were later to reckon) shortened the war by two or even three years. But even before the fall of Berlin, senior code-breakers – figures such as director Edward Travis and his deputy Nigel de Grey – were looking ahead to the sort of world that was being shaped. And they saw the terrible hazards.

Bletchley Park, Buckinghamshire, the headquarters of the Allied cryptographers during the Second World War.(Photo by Evening Standard/Getty Images)

Europe, which had regarded itself as the peak of human civilisation, had been blasted back to the dark ages. Cities were shattered. Food was painfully scarce. Millions of displaced people were harried and hounded. And deep in the forests of eastern Europe, the full horror of the Nazi genocide of the Jews had been uncovered. The continent was suffused with darkness and blood.

Now Stalin’s place-men were embedding themselves, as Churchill put it in his famous 1946 ‘Iron Curtain’ speech, “from Stettin in the Baltic to Trieste in the Adriatic”. The fear of the code-breakers – listening to the faltering heartbeat of this wounded continent – was that war could so easily reignite.

British Prime Minister Winston Churchill delivers a speech at Westminster College that addressed the Communist threat, and in which he uttered the now-famous phrase 'Iron Curtain,' Fulton, Missouri, March 5, 1946. (Photo by George Skadding/The LIFE Picture Collection/Getty Images)
Churchill gives his 1946 'Iron Curtain' speech in Missouri, USA, speaking of a divide across Eastern Europe. (Photo by George Skadding/The LIFE Picture Collection/Getty Images)

A new age of computing

From the inter-war years of the 1930s to the end of WW2, British code-breaking had evolved from a small-scale speciality, essentially a cottage industry, into an almost industrial concern, decoding thousands upon thousands of messages, and all under a total blanket of secrecy. Bletchley had run a world-wide operation; secret listeners in stations on every continent intercepting every coded communication, listening to every enemy plan and manoeuvre.

On top of this, the code-breakers had (almost as a side-effect) kick-started a new age of computing. Their efforts to find a mechanised means of decoding Nazi messages led to the creation of the first programmable proto-computers.

Even though many of the younger recruits were now to head off into new lives – in government, the Civil Service, in the realms of science and mathematics – there were invisible threads that would draw them back into the secret realm. For instance, Professor Max Newman and Alan Turing – who in the 1930s were tutor and student at Cambridge, and then at Bletchley Park pioneered a new electronic age of cryptography – went to the University of Manchester and the National Physical Laboratory, helping to develop newer, more complex computers. They and other boffins such as Jack Good were in constant contact with the code-breakers who stayed on.

Bletchley Park itself was slowly cleared out; sensitive decrypts were consigned to huge bonfires. The locals in the town were left none the wiser about who all these thousands of young people had been, or what they had done.

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Alan Turing’s trial for ‘gross indecency’ and subsequent tragic suicide in 1954 are now part of the fabric of modern British history; less well-known is the fact that the people who steadfastly stood by him in those terrible days – among them code-breakers Joan Clarke and Hugh Alexander – were by then at the centre of an astonishing secret service that he had helped to shape.

Alan Turing was a pioneer in the new age of computing, having carried out vital code-breaking work at Bletchley Park during the Second World War. (Photo by Fine Art Images/Heritage Images/Getty Images)

The earliest days of GCHQ

What had once been known as ‘The Government Code and Cypher School’ became the ‘London Intelligence Centre’. And by 1947, some internal classified memos were referring to it as GCHQ – Government Communications Headquarters. This acronym was never referred to publicly at all until 1976, when journalists at Time Out magazine revealed its existence.

These days, the business of code-breaking is carried out at GCHQ in Cheltenham. The operation was moved there in the early 1950s. But before this, in the immediate postwar years, when it was initially decided that Bletchley Park should be packed up and the remaining code-breakers brought closer to London, the cryptanalysts had a sojourn in the heart of John Betjeman’s Metroland.

The site was at Eastcote, a former RAF base well-camouflaged in a leafy middle-class London suburb on the Metropolitan Line. The code-breakers took some of their revolutionary machinery with them. Secrecy was still absolute. The area’s bowler-hatted city commuters, who frequented Eastcote’s mock-Tudor village pubs at the end of their working days, would have had no idea that their fellow drinkers were engaged in vital confidential work of global importance.

In those immediate postwar years, senior Bletchley figures such as Hugh Alexander and Joan Clarke (Alan Turing’s former fiancée) had understood that peace would be an illusion in many parts of the world. From conflicting ideologies to the disintegration of empires, the potential flashpoints were limitless. And after August 1945, as the mushroom clouds rose and the skies above Nagasaki and Hiroshima flashed and darkened with nuclear fury, the code-breakers were also considering the threat of atomic apocalypse.

Soviet Russia under Stalin did not yet possess nuclear weaponry. But it would not take them long to acquire it. The first of their nuclear tests took place in the plains of Kazakhstan in 1949. There were secret wireless intercept operatives working before that on the borders of Afghanistan, Iran and Azerbaijan. Their intelligence was being fed back to that incongruous leafy suburb, to a base hidden so well behind wide avenues of 1930s houses that most could never have known it was there.

The lives of the postwar code-breakers

Life at Eastcote – though intensely pressurised – still had the youthful flavour of Bletchley. Even the most owlish of cryptology experts loved their cricket and their tennis. Music was very important to many of them too; in the immediate postwar years, many new recruits were sworn jazz aficionados. There was one major difference though: the vast majority of Bletchley’s talented female code-breakers had left. In the late 1940s, no matter how intellectually dazzling, women were expected to be home-makers.

Elsewhere, before Britain’s empire began to dissolve, there were cryptographers and interceptors in Hong Kong, and in Egypt, or sitting in secret stations in Ceylon and India, who wanted to make sure that they could hold on to these invaluable outposts. For it was from these that they could track developments in China, and in soviet central Asia.

One such secret listener was later to become a defining novelist of his generation. As a very young man, Alan Sillitoe, who had been working in a Nottingham bicycle factory, was called up for National Service. He had a gift for incredibly fast Morse code transcription and translation. He found himself deep in the jungles of Malaya, on eerie night-shifts in a simple wooden hut, earphones on, listening to messages between pilots, conversations between officials. Sometimes, surreally, from nowhere, his headphones would be filled with random snatches of classical music.

Alan Sillitoe, one of the important British writers of the postwar era, worked as a code-breaker in the years following the Second World War. (Photo by Evening Standard/Getty Images)

Elsewhere, American code-breakers were able to take full advantage of Britain’s colonial network, piggy-backing on those secret stations, to gather up their own intelligence on Soviet manoeuvres. In most other areas, the ‘special relationship’ between the US and the UK was pretty much non-existent, a PR fantasy. But there was a genuine bond of respect and affection between British and American code-breakers.

This was perhaps just as well. For in those unstable postwar years, they happened across a secret so terrible, it initially had to be kept from President Truman and British Prime Minister Clement Attlee. A captured Soviet codebook had enabled a small (and ultra-secret) team of cryptographers to penetrate Russian diplomatic messages. And these revealed that there were double agents working at the heart of Washington and deep within Britain’s security services.

It took some time to dig further to establish identities: but it was a tiny core of British code-breakers who were the first to flag up Cambridge Spies Guy Burgess and Donald Maclean. The others would follow.

The stress of code-breaking as a career was intense; even veterans such as Frank Birch – who had been breaking codes since the First World War, and who in the early 1940s was one of the chief architects of the incredibly close relationship with US code-breakers – had to have a diversionary hobby; his was particularly colourful.

When not burrowing into fiendish codes, Birch was a talented actor and director. He staged French farces in the West End, and in the early 1950s, he had a part in a film comedy Will Any Gentlemen? alongside Sid James.

Elsewhere, as with Bletchley, this newly regenerated GCHQ held on to its talented chess champions. In 1954, at the Hastings international chess tournament, Hugh Alexander took on the Soviet grandmasters – and won an astounding victory. They had no conception that this man spent his days levering his way into Russian codes. Or indeed had been pivotal in Bletchley’s Hut 8 throughout the Battle of the Atlantic.

By the time GCHQ moved to Chelteham, it was a vital part of defence, says Sinclair McKay. (Photo by David Goddard/Getty Images)

By the time GCHQ made its move to Cheltenham in the early 1950s – in part a precaution against nuclear strike on London, in part because some of the code-breakers loved the horse-racing – it had established itself as possibly the most vital link in the defence of the realm.

Sinclair McKay’s book, The Spies of Winter (Aurum Press, 2017) tells the story of the GCHQ code-breakers and how they used new technology to expand the horizons of cryptography in order to defend the nation during the Cold War years and maintain the fragile peace in a world now under the shadow of nuclear holocaust


This article was first published by HistoryExtra in June 2017