In the decades-long process of European integration, the UK was a founding member of the alliance called the Western European Union, established with the London and Paris Conferences in 1954. In 1960 the UK was one of the seven founding members of the European Free Trade Association (EFTA), but in 1973 it left to join the European Communities (EC). When the EC became the European Union (EU) in 1992, the UK was one of the 12 founding member states. The Treaty of Lisbon, signed in 2007, forms the constitutional basis of the European Union since then.