Was there a referendum in the UK to join the EU in 1973?

No, but the UK did hold a referendum on whether to remain a member of the European Community in 1975. The UK joined the European Economic Community in 1973 but the question of membership was not then put to a popular vote (instead it was decided in Parliament). The Labour Party won the General Election in 1974 after promising in its election manifesto that it would hold a referendum on whether the UK should continue to be a member (on renegotiated terms) or leave the EU entirely. The referendum was held on 5 June 1975. Just over 67% of those who voted cast their vote in support of continued membership, and the UK remained a part of European integration until it left in 2020.