This text analyzes British official thinking behind the UK's standing aloof from the moves after 1945 towards European economic collaboration, leading to the establishment of ECSC and the EEC in the 1950s. It deals with the later change of tack (1961), covers the organization in Whitehall for the negotiations with the Communities, and the major problem areas - the Commonwealth, British agriculture, financial implications of British membership, sovereignty, and the future of EFTA.