Hanssen, who was arrested in February, 2001, and was sentenced to life imprisonment in May, 2002, was not a rebel with a romantic attachment to Communism, like the British double agents Kim Philby, Guy Burgess, and Donald Maclean.

NEWYORKER: Double Lives

In early 1951, Liddell notes that evidence has come in suggesting Foreign Office man Donald Maclean may be a Communist spy.

BBC: Cambridge Spies: MI5 diaries revealed