Dearlove calls the Mitrokhin archive the most revelatory Cold War espionage archive that exists to this day.
“The Matrokian archive is probably the most revelatory archive that exists to this day of Cold War espionage, and a whole range of cases are described, successful KGB cases, described in detail.”
Dearlove describes Angleton's nihilistic theory that Western services were thoroughly penetrated and couldn't match Soviet penetrations.
“So there was a very, very nihilistic group which was represented in most of the major Western services, particularly in The US and to an extent in The UK.”