Harold Adrian Russell "Kim" Philby (1

January 1912 – 11 May 1988) was a British intelligence officer and a double

agent for the Soviet Union. In 1963 he was revealed to be a member of the

Cambridge Five, a spy ring which passed information to the Soviet Union during

World War II and in the early stages of the Cold War. Of the five, Philby is

believed to have been most successful in providing secret information to the

Soviets.

He was also responsible for tipping off two other

spies under suspicion of espionage, Donald Maclean and Guy Burgess, both of

whom subsequently fled to Moscow in May 1951. The defections of Maclean and

Burgess cast suspicion over Philby, resulting in his resignation from MI6 in

July 1951. He was publicly exonerated in 1955, after which he resumed his

career as both a journalist and a spy for SIS in Beirut. In January 1964,

having finally been unmasked as a Soviet agent, Philby defected to Moscow,

where he lived until his death in 1988.