MI6 officers concluded that Michael Foot had been used by the Soviets for disinformation purposes

MI6 believed that Michael Foot had been a paid informant of the Soviet Union and was prepared to warn the Queen of his “KGB history” when he stood to become prime minister, its officers have revealed in a new book.

The British intelligence apparatus concluded that the evidence presented by a Soviet defector about the Labour leader’s links with the KGB was strong enough to warrant the unprecedented constitutional action.

The book, The Spy and the Traitor, presents the first corroboration by MI6 officers of the allegations made by the Soviet defector Oleg Gordievsky that Foot had received a series of clandestine payments from the KGB, which classed him as an “agent” and “confidential contact”.

Ben Macintyre on double agent Oleg Gordievsky

They concluded that while Foot had not been a