John Cairncross Ziua nașterii, data nașterii

John Cairncross (25 July 1913 – 8 October 1995) was a British civil servant who became an intelligence officer and spy during the Second World War. As a Soviet double agent, he passed to the Soviet Union the raw Tunny decryptions that may have influenced the Battle of Kursk. He was alleged to be the fifth member of the Cambridge Five. He was also notable as a translator, literary scholar and writer of non-fiction.

The most significant aspect of his work was helping the Soviets defeat the Germans in battle during the Second World War; he may also have told Moscow that the US was developing an atomic bomb. Cairncross confessed in secret to MI5's Arthur S. Martin in 1964 and gave a limited confession to two journalists from The Sunday Times in December 1979. He was given immunity from prosecution.

According to The Washington Post, the suggestion that John Cairncross was the "fifth man" of the Cambridge ring was not confirmed until 1990, by Soviet double-agent Oleg Gordievsky. This was re-confirmed by former KGB agent Yuri Modin's book published in 1994, My Five Cambridge Friends Burgess, Maclean, Philby, Blunt, and Cairncross by Their KGB Controller.