The Labour Party is a centre-left political party in the United Kingdom that has been described as an alliance of social democrats, democratic socialists and trade unionists. The Labour Party was founded in 1900, having grown out of the trade union movement and socialist parties of the 19th century. It overtook the Liberal Party to become the main opposition to the Conservative Party in the early 1920s, forming two minority governments under Ramsay MacDonald in the 1920s and early 1930s. Labour served in the wartime coalition of 1940–1945, after which Clement Attlee's Labour government established the National Health Service and expanded the welfare state from 1945 to 1951. Under Harold Wilson and James Callaghan, Labour again governed from 1964 to 1970 and 1974 to 1979. In the 1990s, Tony Blair took Labour to the centre as part of his "New Labour" project, which governed the UK under Blair and then Gordon Brown from 1997 to 2010. Labour is currently the Official Opposition in the Parliament of the United Kingdom, having won the second-largest number of seats in the 2017 and 2019 general elections. The Labour Party is currently the largest party in the Welsh Assembly, forming the main party in the current Welsh government. The party is the third-largest in the Scottish Parliament. Labour is a member of the Party of European Socialists and Progressive Alliance, holds observer status in the Socialist International, and sits with the Progressive Alliance of Socialists and Democrats in the European Parliament. The party includes semi-autonomous Scottish and Welsh branches, and supports the Social Democratic and Labour Party in Northern Ireland, although it still organises there. As of 2017, Labour had the largest membership of any party in Western Europe.