The Conservative Party, officially the Conservative and Unionist Party and also known colloquially as the Tories or simply the Conservatives, is a centre-right political party in the United Kingdom. The governing party since 2010, it holds an overall majority in the House of Commons with 365 Members of Parliament. It also has 234 members of the House of Lords, 4 members of the European Parliament, 31 Members of the Scottish Parliament, 11 members of the Welsh Assembly, 8 members of the London Assembly and 7,440 local councillors. The Conservative Party was founded in 1834 from the Tory Party—the Conservatives' colloquial name is Tories—and was one of two dominant political parties in the 19th century, along with the Liberal Party. Under Benjamin Disraeli, it played a preeminent role in politics at the height of the British Empire. In 1912, the Liberal Unionist Party merged with the party to form the Conservative and Unionist Party. In the 1920s, the Labour Party surpassed the Liberals as the Conservatives' main rivals. Conservative Prime Ministers, most notably Winston Churchill and Margaret Thatcher, led governments for 57 years of the 20th century. Positioned on the centre-right of British politics, the Conservative Party is ideologically conservative. Different factions have dominated the party at different times, including one nation conservatives, Thatcherites, and liberal conservatives, while its views and policies have changed throughout its history. The party has generally adopted liberal economic policies—favouring free market economics, limiting state regulation, and pursuing privatisation—although in the past has also supported protectionism. The party is British unionist, opposing both Irish reunification and Welsh and Scottish independence, and historically supported the maintenance of the British Empire. The party includes those with differing views on the European Union, with Eurosceptic and pro-European wings. On social policy, it has historically taken a more socially conservative approach, though this has receded over recent decades. In foreign policy, it favours a strong military capability, being supportive of British participation in NATO. The Conservatives are a member of the International Democrat Union and the Alliance of Conservatives and Reformists in Europe, and sit with the European Conservatives and Reformists (ECR) parliamentary group. The Scottish, Welsh, Northern Irish and Gibraltarian branches of the party are semi-autonomous. Its support base consists primarily of middle-class voters, especially in rural areas of England, and its domination of British politics throughout the twentieth century has led to it being referred to as one of the most successful political parties in the Western world.