A KGB officer who became one of the cold war's most important defectors. Lyalin worked for Department V, a KGB outfit that specialised in sabotage and assassinations. He was posted to London in 1969, ostensibly joining a Soviet trade mission, after a stint in Klaipeda on the Baltic coast.
Unlike Oleg Gordievsky, who later passed secrets to MI6 for ideological reasons, Lyalin's defection was personal. He walked into a police station and declared himself a KGB officer, hoping to be formally expelled so he could return home as a hero and divorce his wife (he was involved with five other women). In return he offered to provide MI5 with information about the KGB's mission in Britain and continue working for it from Moscow.
After being arrested for driving erratically down Tottenham Court Road, and with his wife contacting his bosses in Moscow questioning his loyalty, he was ordered home to face "severe administrative action". Defection became his only option. Three weeks later the British government ordered the mass expulsion of 105 Soviet spies.
His defection helped restore MI5's confidence after Kim Philby, a British spy, was revealed in 1963 to be working for Moscow. Richard Kerbaj tells Lyalin's story in "The Defector" (Blink, 304 pages), drawing on recently declassified intelligence.
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