Klaus Fuchs was a brilliant theoretical physicist. Quiet and withdrawn, he wore round spectacles and had an uncanny ability to attract female sympathy. He was also a dedicated communist, and the most important atomic spy of the post-war period. Born in Germany, Fuchs settled within the British university system after fleeing Nazi Germany before the war. Becoming a British citizen and signing the Official Secrets Act in 1942, he worked on the atomic bomb as part of the Manhattan Project in America. He was one of the few scientists with an overview of the whole project, including the perplexing problem of trigger design for detonation of the main device. After the war, he returned to the UK to work at the Atomic Energy Research Establishment at Harwell. But unbeknownst to the government, Fuchs had long been passing secret information to the Soviets. In America he would drive around in his second-hand blue Buick with a stash of papers on the passenger seat, containing closely guarded secrets about the most devastating weapon ever created. Still he was not caught. In England, he used prearranged signals to meet his Soviet contacts in pubs. To one he offered: ‘I think the best British heavyweight of all time is Bruce Woodcock.’ On cue, the contact replied: ‘Oh no, Tommy Farr is certainly the best.’ Following a ‘complete dog’s breakfast’ of an investigation by MI5 in late 1949, Fuchs finally confessed early the following year.61
According to Sillitoe, suspicions about Fuchs first arose in August 1949 as a result of ‘Venona’, a programme by British and American codebreakers to unravel wartime messages sent by the KGB that were proving uniquely vulnerable. The following month, J.C. Robertson, head of counter-espionage at MI5, and Arthur Martin, the MI5 liaison with GCHQ, began working with security officers at Harwell to investigate Fuchs’s background. Jim Skardon, an MI5 interrogator, questioned Fuchs, while MI5 listened in on his phone calls and followed him with teams of ‘watchers’.62 As is so often the case, intercept material, this time gathered from Venona, was too sensitive to be openly used in court. Under pressure from the FBI to act, MI5 needed to gather its own physical evidence, ideally based on his contacts with Soviet handlers.
Percy Sillitoe grew frustrated. By his own admission, the ‘investigation produced no dividends’. Running out of options and unable to use Venona, he even resorted to asking the senior official at the Ministry of Supply ‘to quietly arrange for Fuchs [sic] departure from Harwell as soon as decently possible’.63 Doing so, however, would have raised suspicious eyebrows from Fuchs’s colleagues and friends, since he was Britain’s star nuclear weapons scientist.
Sillitoe was furious when he learned how long Fuchs had been operating as a spy for the Soviets. Together with Dick White, a future head of MI5 and then MI6, he had to make the short but uncomfortable journey to Downing Street to break the bad news to the prime minister. White insisted that they had been thorough – four separate investigations had failed to find anything incriminating – but Attlee was unimpressed. The prime minister ‘could only reflect that, if MI5’s four investigations had produced no evidence, it was a reflection upon the investigation not the evidence’.64
In early 1950, Sillitoe delivered a brief to Attlee. It was described by the service as ‘merely factual’, but was clearly designed to defend MI5’s actions. A month later, when Sillitoe saw the prime minister again, he found him in ‘fighting form’ and proposing ‘to defend the department’. To aid the prime minister with this defence, Sillitoe left some ‘debating points’ in Number 10 and went away satisfied that he had Attlee’s support, that the prime minister ‘had no intention of allowing an enquiry into the activities of the Security Service’, and was ‘entirely satisfied with the work of the department’.65 He had guessed right. Just three days later Attlee stood in front of the House of Commons and stalwartly defended MI5, confidently asserting to the nation that ‘I do not think there is anything that can cast the slightest slur on the Security Services.’66 This was the first time a prime minister had discussed intelligence and security at such length in Parliament.
There was one snag. Sillitoe later admitted that he had not given Attlee the whole story. The MI5 brief was written in part by Roger Hollis, MI5’s expert in Soviet espionage and the man who had repeatedly cleared Fuchs.67 It contained certain strategic inaccuracies and misrepresentations, and these flaws shaped Attlee’s speech to Parliament. Unsurprisingly, it portrayed MI5 as having been proactive and vigilant by conducting numerous checks on Fuchs and unearthing no evidence. Fudging key dates, it tried to pass the buck to other government departments, including the Ministry of Aircraft Production and the Ministry of Supply.68 MI5 hoped to weasel out of its central role by insisting to the prime minister that ‘the responsibility of the Security Service is limited to tendering advice’.69 Yet the advice tendered was that Fuchs posed only a ‘very slight’ security risk.70
MI5’s brief informed Attlee that Fuchs had become ‘a close friend’ of a German while interned in Canada in 1940. Significantly, however, it stopped short of revealing the identity of this German friend. He was Hans Kahle – ‘such a notorious Communist that his name may well have been known to Attlee’.71 The significance of this had previously been dismissed by Roger Hollis.72 The fact that he strangely ‘over-looked’ the connections between one of Britain’s most damaging post-war spies and one of the decade’s most active communists would later become one of the drivers for lingering suspicions about the loyalties of Hollis himself, with some alleging that he had spied for Moscow. Moreover, the prime minister was informed that until 1949 there was no confirmation of Fuchs’s membership of the German Communist Party. Once again, this was not the full story – Attlee was not told that MI5 had ‘access to the Gestapo records since 1946 but had failed to consult them’.73
Sillitoe and his subordinates pointed to everyone except MI5. They went on to blame the police, the constraints of parliamentary democracy, and the importance of using skilled foreigners during the war. These arguments seemingly held weight with the prime minister, who adopted the parliamentary democracy line in his address to the House of Commons. Directly summarising MI5’s suggestions, he told MPs, ‘I am satisfied that, unless we had here the kind of secret police they have in totalitarian countries, and employed their methods, which are reprobated rightly by everyone in this country, there was no means by which we could have found out about this man.’74
MI5 also urged Downing Street to counter criticism of its performance in the press, Sillitoe complaining to Attlee, ‘There has been a great deal of uninformed criticism of the Security authorities in relation to the FUCHS case.’ In the circumstances, he felt, the prime minister ‘may consider it advisable that some statement should be made in the House of Commons putting the facts into their proper perspective’. MI5 even went on to suggest exactly what the prime minister should say.75 Arguably, MI5 was rather better at public relations than at security. Behind the scenes, it was successfully persuading documentary-makers not to make films about Fuchs.76 Influenced by his brief, Attlee did indeed argue that ‘there is a great deal of loose talk in the Press suggesting inefficiency on the part of the security services. I entirely deny that.’ He praised MI5 for acting ‘promptly and effectively as soon as there was any line which they could follow’.77