Oleg Gordievsky, who was the top K.G.B. agent in London until he defected to the West in 1985 and revealed himself as a longtime double agent for British intelligence — making him one of the most highly placed Western spies…

Oleg Gordievsky, who was the top K.G.B. agent in London until he defected to the West in 1985 and revealed himself as a longtime double agent for British intelligence — making him one of the most highly placed Western spies…