Defend the Realm : The Authorized History of MI5

For over 100 years, the agents of MI5 have defended Britain against enemy subversion. Their work has remained shrouded in secrecy—until now. This first-ever authorized account reveals the British Security Service as never before: its inner workings, its clandestine operations, its failures and its triumphs.

Christopher Andrew is Britain’s leading historian of intelligence, professor of modern and contemporary history and chair of the faculty of history at Cambridge University. He is also chair of the British Intelligence Study Group, coeditor of Intelligence and National Security, former visiting professor at Harvard, Toronto, and the Australian National University, and a regular presenter of BBC Radio and TV documentaries. His thirteen previous books include The Mitrokhin Archive, volumes 1 and 2, and a number of groundbreaking studies on the use and abuse of secret intelligence in modern history.