The disappearance of diplomats Guy Burgess and Donald Maclean in May 1951 rocked the British establishment and lead ultimately to the unmasking of the notorious Cambridge spies - a network of brilliant graduates who had penetrated the heart of British power to spy for the Soviet Union.
As the Government finally opens its archives on Burgess and Maclean, held secret for nearly 65 years, Martha Kearney examines the papers to discover how Foreign Office Mandarins reacted to the horrifying discovery of spies within their midst.
Heavily criticised at the time for saying too little in public and engaging in a cover-up, we can now learn what was being said behind closed doors. Donald Maclean had been under suspicion for leaking documents from Washington during the war and was due to be confronted about it when he disappeared. We can now follow events as the net closed in around him- and see how attention soon turned to Kim Philby, Maclean's fellow spy, still at his post in the Washington Embassy.
The archives include files from the Foreign Office, Cabinet Office and Security Service but, in this programme, Martha focuses mostly on the Foreign Office as an institution and what the papers reveal about its atmosphere at the time - the Old Boy network mode of recruitment and management, and the soul searching that went on in the wake of the spy scandal.
Producer: Deborah Dudgeon
Series Producer: David Prest
A Whistledown production for BBC Radio 4.