of the British electorate, which is lower than in all European countries except for Poland and Latvia. Overall membership to a political party has been in decline since the 1950s. In 1951, the Conservative Party had 2.2 million members, and a year later in 1952 the Labour Party reached their peak of 1 million members (of an electorate of around 34 million). The table below details the membership numbers of political parties that have more than 5,000 members. No data could be collected for the four parties of Northern Ireland: the DUP, UUP, SDLP, and Sinn Féin. However, in January 1997, it was estimated that the UUP had 10,000 – 12,000 members, and the DUP had 5,000 members. In December 2020, the UK Independence Party had 3,888 members. In June 2019, Reform UK claimed to have 115,000 registered supporters. Local government The UK is divided into a complex system of local governance. Former European Union membership The United Kingdom first joined the then European Communities in January 1973 by the then Conservative Prime Minister Edward Heath, and remained a member of the European Union (EU) that it evolved into; British citizens, and other EU citizens resident in the UK, between 1979 and 2019 elected members to represent them in the European Parliament in Brussels and Strasbourg. The UK's membership in the Union has been a major topic of debate over the years and has been objected to over questions of sovereignty, and in recent years there have been divisions in both major parties over whether the UK should form greater ties within the EU, or reduce the EU's supranational powers. Opponents of greater European integration are known as "Eurosceptics", while supporters are known as "Europhiles". Division over Europe is prevalent in both major parties, although the Conservative Party is seen as most divided over the issue, both whilst in Government up to 1997 and after 2010, and between those dates as the opposition. However, the Labour Party is also divided, with conflicting views over British adoption of the euro whilst in Government (1997–2010). British nationalists have long campaigned against European integration. The strong showing of the eurosceptic UK Independence Party (UKIP) since the 2004 European Parliament elections has shifted the debate over UK relations with the EU. In March 2008, Parliament decided to not hold a referendum on the ratification of the Treaty of Lisbon, signed in December 2007. This