Paperback edition of this first ever authorized history of the British Security Service, aka MI5, written by this independent historian. The resulting book reveals the precise role of MI5 in 20th century British history, from its foundation in 1909, through two world wars, up to and including its present roles in counter espionage and terrorism.

Christopher Andrew is Professor of Modern and Contemporary History and former Chair of the Faculty of History at Cambridge University. He is also chair of the British Intelligence Study Group, Founding Co-Editor 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 fifteen previous books include The Mitrokhin Archive volumes 1 and 2, and a number of path-breaking studies on the use and abuse of secret intelligence in modern history.