 Penney did not have any knowledge of such committee until he was approached by Marshal of the Air Force Lord Portal, to lead the clandestine efforts. The project was code-named High Explosive Research (or HER). In May 1947, Penney was appointed as the director to lead the programme, based at the Royal Armament Research Development Establishment (RARDE) at Fort Halstead and the Royal Arsenal at Woolwich (AWE). In short span of time, Penney assembled a team to initiate the work on atomic weapons, firstly preparing a report on describing the feature, science and idea of the American Fat Man implosion bomb. Penney broke down the development tasks required to replicate it, and identifying outstanding questions that required further research on nuclear weapons. The report entitled, "Plutonium Weapon – General Description" was roughly equivalent in terms of scientific data and reports that were provided to the Soviet nuclear program by Klaus Fuchs.
