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A number of Security Service files released to the National Archives (new window) on 2 March 2007 concerned British atomic scientists suspected of involvement in espionage.
File refs KV 2/2579-2585
Davison was a brilliant mathematician whose role in the development of the atomic bomb, through his calculations on critical mass theory, is still largely unrecognised today. He was, however, of key interest to the Security Services because of his unusual family background. He was born in Russia to a second generation British emigrant family, who had retained their British nationality. As recorded in KV 2/2579 (1943-1951), he left Russia for Britain in 1938 when his residence visa was not renewed, though his family stayed behind.
Working first for the Royal Aircraft Establishment, and then with Professor Rudolf Peierls at Birmingham University on the Tube Alloys project, his access to military secrets was always worrying. He was working at the Atomic Energy Research Establishment, Harwell, at the same time as the Nunn May and Pontecorvo atom spy cases, and so the Security Service kept a close watch on his activities, and made lengthy investigations into the possible risk he posed.
Joining Harwell in September 1947, the Service agonised over his case, and months later was still trying to work out its position on him holding such a sensitive post. Minute 24 records in October 1948: "He is described...as an "outstanding mathematician" and as such worked...with the Tube Alloy team with Professor Peierls in Birmingham from 1941 to 1944. During the latter period he is stated to have made a marked contribution to the theory of the critical size of the atomic bomb...While there is admittedly no positive ground whatever for suspicion against him, the circumstances of the case suggest strongly that we should know more about him than we do."
A watch was mounted on Davison's post, taken off, then hastily re-imposed after the worries generated by the Pontecorvo defection case. This raised the assumption that Pontecorvo would have informed the Russians about Davison's key role, and about his Russian family, and that this might have made Davison vulnerable to Soviet pressure. The counter view was that the Russians must have known about Davison for some time before Pontecorvo defected.
Prime Minister Attlee had asked to be informed about foreign scientists working in strategic posts in the UK, and so in January 1951 the Security Service's Director-General Percy Sillitoe informed Attlee about the Davison case. Sillitoe's brief and Attlee's response are at serials 129a and 131a. There is an account of a meeting with Attlee on 30 January 1951 at serial 135a: "It was decided that in view of the great importance attaching to Davison's work...he should not be transferred from his present duties. The responsibility for any ...political consequences was accepted by the Prime Minister personally."
Subsequently, the file includes a report of William Skardon's interview with Davison on 23 February 1951. A summary of Skardon's report was sent to Attlee (KV 2/2580, serial 158a). This file also includes a report of Klaus Fuchs' view of Davison at serial 169a. The rest of the file is largely taken up with intercepted letters, particularly those from Davison's father, which were closely scrutinised for hidden messages and for any indication of pressure being applied to Davison through his family. This anxiety increased in 1952 when Davison's father was persuaded to become a naturalised Russian subject (KV 2/2581, 1951-1952, minute 221). There was a debate as to whether the new Prime Minister, Churchill, should be told, but in the event the Home Secretary was briefed in April 1952 (serial 236).
At around this time Davison's wife returned to her native Canada for health reasons, and there was a concern that Davison too might leave the UK. The case came to the Defence Committee, and is recorded in a confidential annex to meeting D(52)10 of October 1952 (serial 305) in KV 2/2582 (1952). In 1952 Davison left Harwell for a year's sabbatical to work again with Peierls at Birmingham. Press reporting of this event portrayed it that Davison had been sacked from Harwell because of his Russian connections - and Davison's indignation at this complete misrepresentation (especially that of the Daily Express) is captured on KV 2/2583 (1952-1953). KV 2/2584 (1953-1954) and KV 2/2585 (1954) cover Davison eventually finding work in Canada and moving to join his wife in Toronto. He died in Canada in 1961.
File refs KV 2/2589-2591
Another atom scientist of Russian origin working in the West was Leo Kowarski, who had worked at the Cavendish Laboratory with Broda and Nunn May, with whom he was a friend. Kowarski's work after the Second World War was chiefly in France, and so there is less Security Service interest in his case that that of Davison. KV 2/2589 (1940-1950) includes a copy of Kowarski's registration card with photograph (serial 29a), and includes correspondence about his case with Kim Philby (serials 38a and 39a). Coverage of the case continues in KV 2/2590 (1950-1952), including at minute 97 of August 1950 details of reports that Kowarski was a Communist. The file continues to 1955 in KV 2/2591.