LONGLISTED FOR THE ORWELL PRIZE FOR POLITICAL WRITING 2021 'One of the best books ever written about intelligence analysis and its long-term lessons' Christopher Andrew, author of The Defence of the Realm: The Authorized History of MI5 'An invaluable guide to avoiding self-deception and fake news' Melanie Phillips, The Times From the former director of GCHQ, Professor Sir David Omand, learn the methodology used by British intelligence agencies to reach judgements, establish the right level of confidence and act decisively. Full of revealing examples from a storied career, including key briefings with Prime Ministers and strategies used in conflicts from the Cold War to the present, in How Spies Think Professor Omand arms us with the tools to sort fact from fiction, and shows us how to use real intelligence every day.