Security Service ‘list’ files
In this release
Leakage of Top Secret Foreign Office Telegrams in the USA: Evidence and Investigation
The Security Service conducted an investigation that led to the unmasking of Donald Maclean. This was sparked by the leaking of six Foreign Office telegrams on the British negotiating position for talks between Churchill, Roosevelt and Stalin, which reached the USSR via an agent known as HOMER. An initial shortlist of possible suspects included Cedric Belfrage, but he was soon ruled out (KV 6/140). As the net closed in on Maclean, an analysis of him as a fit for HOMER was produced. He soon became the top suspect and reference was made to HOMER’s wife being in New York (KV 6/142). The enquiry developed, and statements were taken from Anthony Blunt, who was later revealed as the fourth member of the spy ring, and Goronwy Rees. The Director General of MI5, Sir Percy Sillitoe, was briefed for a meeting with J Edgar Hoover of the FBI (KV 6/143). Philby became persona non grata with the CIA and Sillitoe exchanged letters with Hoover suggesting that the CIA be briefed on events (KV 6/144). A timeline was produced summarising the investigation (KV 6/145).