Cambridge spy Guy Burgess was a supreme networker. He also set a gold standard for conflicts of interest, working variously for the BBC, MI5, MI6, the War Office, the Ministry of Information and the KGB. Yet Burgess was never challenged by Britain's spy-catchers: his superiors were convinced he was too much of a liability to have been recruited by Moscow. Now, with a major new release of hundreds of files into the National Archives, Purvis and Hulbert reveal just how this charming establishment insider was able to fool everyone for so long, without suspicion, all the while working for the KGB.