Oleg Gordievsky

Oleg Antonovich Gordievsky (; born 10 October 1938) is a former colonel of the KGB who became KGB resident-designate (''rezident'') and bureau chief in London.

He was a double agent, providing information to the British Secret Intelligence Service (MI6) from 1974 to 1985. After being recalled to Moscow under suspicion, he was exfiltrated from the Soviet Union in July 1985 under a plan code-named Operation Pimlico. The Soviet Union subsequently sentenced him to death ''in absentia''. Provided by Wikipedia