13. Kim Philby and the Cambridge Five
Kim Philby, a British intelligence officer, was a member of the Cambridge Five, a group of Soviet spies active from the 1930s to the 1950s. Recruited by Soviet intelligence in 1934, Philby passed state secrets to the Soviet Union for decades. His exposure in 1963 shocked the West, leading to his defection to Moscow. For more details, see the MI5’s account of the Cambridge Five. (mi5.gov.uk)
