Ronald Koorm has given talks and lectures on the codebreaking outstations for several years ‒ this is the last piece of the amazing Bletchley jigsaw. Full of extraordinary stories: who built the first electronic digital computer? Tommy Flowers ‒ but not at Bletchley ‒ at Dollis Hill! The first detailed study of the Bombe registers at the National Archives, which brings a new understanding of the perennially fascinating Bletchley story. Ronald Koorm explores the complex relationship between Bletchley Park and its support codebreaking outstations, the background to the Enigma encoding machine, and how Eastcote became the largest codebreaking outstation during the war. He analyses the development of improvements on Alan Turing's Bombe machine, the contribution of the WRNS (Wrens) in operating the machines, and some of the social history showing how those Wrens from varying social backgrounds displayed outstanding teamwork under immense pressure at the codebreaking sites. Post-war, Eastcote became GCHQ prior to moving to Cheltenham, and there were multiple uses of the site, including Cold War counter-inelligence operations. The author explores the link between Alan Turing and others in terms of the quest for Artificial Intelligence, and how talented individuals during the war helped shape the future. Backing Bletchley includes previously unpublished diagrams, charts and illustrations of the story of the outstations, which shed further light on the extraordinary historic events that occurred at them.