FULLY UPDATED CENTENARY EDITION 'An important book' Max Hastings, Sunday Times 'An intriguing history of covert surveillance ... thoroughly engaging' Daily Telegraph GCHQ is the largest and most secretive intelligence organisation in the UK, and has existed for 100 years - but we still know next to nothing about it.In this ground-breaking book - the first and most definitive history of the organisation ever published - intelligence expert Richard Aldrich traces GCHQ's development from a wartime code-breaking operation based in the Bedfordshire countryside into one of the world leading espionage organisations.Packed with dramatic spy stories, GCHQ also explores the organisation's role behind the most alarming headlines of our time, from fighting ISIS to cyberterrorism, from the surveillance state to Russian hacking. Revelatory, brilliantly written and fully updated, this is the crucial missing link in Britain's intelligence history.