who was prime minister when britain joined the common market
United Kingdom European Communities membership referendum, 1975 The United Kingdom European Communities referendum of 1975, also known as the Common Market referendum and EEC membership referendum was non-binding referendum held on 5 June 1975 in the United Kingdom to gauge support for the country's continued membership of the European Communities (EC)—often known at the time as the "Common Market"—which it had entered on 1 January 1973 under the Conservative government of Edward Heath. Labour's manifesto for the October 1974 general election had promised that the people would decide "through the ballot box"[1] whether to remain in the EC.