Newly-released files have disclosed fresh details of one of Britain's biggest spying scandals, in which two members of the "Cambridge Five" defected to the Soviet Union during the Cold War.
The files show how MI5 and MI6, backed up by senior Foreign Office officials, engaged in frantic attempts to prevent any information about Moscow’s “magnificent five” spies from being disclosed to the British public and even to the US government.
The five were contemporaries at Cambridge University in the 1930s, and were attracted to communism mainly because of the Wall Street crash and in opposition to appeasers in the British and other governments during the rise of Hitler.
The files also show in detail the reaction of the then US government to the scandal.
According to them, two members of the Cambridge spy ring were so drunken and unstable that US officials were stunned they had been employed by the Foreign Office.
The defection of Guy Burgess and Donald Maclean to Moscow in 1951 left the US State Department's confidence in British officials "severely shaken".
The files also show that both Burgess - who worked at the BBC before joining the Foreign Office - and Maclean had been involved in drunken escapades.