This history of the world's largest and most powerful intelligence service, the KGB, from its origin after the Russian revolution to the present day, analyzes its operations against subjects as diverse as the EEC, Margaret Thatcher, Solidarity and Libya. This study also provides an insight into Gorbachev's relations with the KGB and examines the disintegration of the Soviet bloc. Christopher Andrew has also written "Secret Service". Gordievsky was a KGB colonel who worked for British intelligence as a penetration agent in the KGB from 1974. He escaped to the West in 1985.