Kim Philby's defection to USSR made public

On 30 July 1963, Kim Philby's defection from MI6 to the Soviet Union was made public. In 2016, the BBC broadcast previously unseen footage of a 1981 lecture he gave to East Germany's Stasi, offering a masterclass in betrayal. Philby, a member of the Cambridge Five spy ring, passed British secrets to the Kremlin during WWII and the Cold War, causing deaths among betrayed agents.