of the Anglo-Canadian Montreal Laboratory. The British mission to the Los Alamos Laboratory led by James Chadwick, and later Rudolf Peierls, included distinguished scientists such as Geoffrey Taylor, James Tuck, Niels Bohr, William Penney, Otto Frisch, Ernest Titterton and Klaus Fuchs, who was later revealed to be a spy for the Soviet Union. As overall head of the British Mission, Chadwick forged a close and successful partnership with Brigadier General Leslie R. Groves, the director of the Manhattan Project, and ensured that British participation was complete and wholehearted. Origin The Government of the United Kingdom is directed by the cabinet, a group of senior government ministers led by the Prime Minister. Most of the day-to-day work of the cabinet is carried out by cabinet committees, rather than by the full cabinet. Each committee has its own area of responsibility, and their decisions are binding on the entire cabinet. Their membership and scope is determined by the Prime Minister. During the post-Second World War period, in addition to standing committees, there were ad hoc committees that were convened to handle a single issue. These were normally short-lived. Each was given a prefix of Gen and a number. Gen 183, for example, was the Committee on Subversive Activities. Between 1945 and 1964, Gen (for general) committees were sequentially numbered from 1 to 881 in order of formation. Prime Minister Clement Attlee, who succeeded Churchill in June 1945, created the Gen 75 Committee on 10 August 1945 to examine the feasibility of a nuclear weapons programme. It was known informally by Attlee as the "Atomic Bomb Committee", although no explicit decision to build one was made until January 1947. The Gen 75 Committee differed from other Gen committees in that its deliberations were not reported to the full cabinet, and were shrouded in secrecy even at that level. The entire subject of nuclear weapons was kept off the full cabinet agenda, and cabinet ministers not attending the meetings may not have even known of its existence. Composition Membership of Gen 75 initially consisted of five ministers: the Prime Minister, Clement Attlee; the Lord President of the Council, Herbert Morrison; the Foreign Secretary, Ernest Bevin; and the President of the Board of Trade, Stafford Cripps. It was soon expanded with the addition of the Lord Privy Seal, Arthur Greenwood, and the Chancellor of the Exchequer, Hugh Dalton. After the Gen 75 Committee decided that