GUY HARTCUP served in the British and Indian Armies 1939-45 after which he took an Honours Degree at Cambridge in 1947. From 1948-60 we worked as an Historian in the Air Historical Branch of the Air Ministry. He then became an English editor with the International Atomic Energy Agency in Vienna from 1961-2. After returning to England the author was an Assistant Historian in the Cabinet Office Historical Section and, finally, was Historian in the Treasury from 1965-76. His books include Code Name Mulberry: the Planning, Building and Operation of the Normandy Harbours; Camouflage: a History of Concealment and Deception in War; Cockroft and the Atom (with T. E. Allibone); The War in Invention: Scientific Developments, 1914-18; The Silent Revolution: Development of Conventional Weapons, 1945-85; Operational Research in the RAF; and The Challenge of War: Scientific and Engineering Contributions to World War Two.