Andrew Cook worked for many years as a foreign affairs and defence specialist, and was aide to George Robertson (former Secretary of State for Defence, now Lord Robertson of Port Ellen and Secretary General of NATO) and John Spellar (former Minister of State for the Armed Forces). The contacts he made enabled the author to navigate and gain access to classified intel-ligence services archives. During his ten years researching this book, he was only the fifth historian to be given special permission, under the 1992 ‘Waldegrave Initiative’ by the Cabinet Office, to examine closed MI6 documents that will never be released, documents not seen by any previous biographer of Reilly. Since working directly as a foreign affairs and defence specialist, Andrew Cook has worked as a professional historian in colleges and universities. He is a regular contributor on espionage history to The Guardian, The Times and BBC History Magazine and has appeared on national radio and television. His next book, M: MI5’s First Spymaster, will be published by Tempus. The author’s Sidney Reilly website is www.sidneyreilly.com. He lives in Bedfordshire.