Oleg Antonovich Gordievsky, CMG 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.

The Secret Intelligence Service (SIS), commonly known as MI6, is the foreign intelligence service of the United Kingdom, tasked mainly with the covert overseas collection and analysis of human intelligence on foreign nationals in support of its Five Eyes partners. SIS is one of the British intelligence agencies and the Chief of the Secret Intelligence Service ("C") is directly accountable to the Foreign Secretary.