While other books have speculated on the history and nature of Britain's intelligence services, this is the first to tell the story through the documents themselves. Only ten years ago access to these original sources would have been impossible; now experts Twigge, Hampshire and Macklin draw on the spies and spymasters' own words from The National Archives' unique intelligence files - including the very latest remarkable releases from MI5. Historical narrative is interwoven with colourful tales from the past that highlight some of the greatest successes and failures along the way, as well as the motives and machinations of those responsible for them. And readers who want to explore the sources for themselves are given all the guidance they need.