The United Kingdom is a unitary state with devolution that is governed within the framework of a parliamentary democracy under a constitutional monarchy in which the monarch, currently Queen Elizabeth II, is the head of state while the Prime Minister of the United Kingdom, currently Boris Johnson, is the head of government. Executive power is exercised by the British government, on behalf of and by the consent of the monarch, and the devolved governments of Scotland and Wales and the Northern Ireland Executive. Legislative power is vested in the two chambers of the Parliament of the United Kingdom, the House of Commons and the House of Lords, as well as in the Scottish Parliament and Welsh and Northern Ireland assemblies. The judiciary is independent of the executive and the legislature. The highest court is the Supreme Court of the United Kingdom.
The UK political system is a multi-party system. Since the 1920s, the two dominant parties have been the Conservative Party and the Labour Party. Before the Labour Party rose in British politics, the Liberal Party was the other major political party, along with the Conservatives. While coalition and minority governments have been an occasional feature of parliamentary politics, the first-past-the-post electoral system used for general elections tends to maintain the dominance of these two parties, though each has in the past century relied upon a third party, such as the Liberal Democrats, to deliver a working majority in Parliament. A Conservative–Liberal Democrat coalition government held office from 2010 until 2015, the first coalition since 1945. The coalition ended following parliamentary elections on 7 May 2015, in which the Conservative Party won an outright majority of 330 seats in the House of Commons, while their coalition partners lost all but eight seats.
With the partition of Ireland, Northern Ireland received home rule in 1920, though civil unrest meant direct rule was restored in 1972. Support for nationalist parties in Scotland and Wales led to proposals for devolution in the 1970s, though only in the 1990s did devolution happen. Today, Scotland, Wales and Northern Ireland each possess a legislature and executive, with devolution in Northern Ireland being conditional on participation in certain all-Ireland institutions. The UK government remains responsible for non-devolved matters and, in the case of Northern Ireland, co-operates with the government of the Republic of Ireland.
It is a matter of dispute as to whether increased autonomy and devolution of executive and legislative powers has contributed to the increase in support for independence. The principal Scottish pro-independence party, the Scottish National Party, became a minority government in 2007 and then went on to win an overall majority of MSPs at the 2011 Scottish parliament elections and forms the Scottish Government administration. A 2014 referendum on independence led to a rejection of the proposal but with 44.7% voting for it. In Northern Ireland, there are also Irish nationalist parties. The largest, Sinn Féin, not only advocates Irish reunification, but its members also abstain from taking their elected seats in the Westminster parliament, as this would entail taking a pledge of allegiance to the British monarch.
The constitution of the United Kingdom is uncodified, being made up of constitutional conventions, statutes and other elements such as EU law. This system of government, known as the Westminster system, has been adopted by other countries, especially those that were formerly parts of the British Empire.
The United Kingdom is also responsible for several dependencies, which fall into two categories: the Crown dependencies, in the immediate vicinity of the UK, and British Overseas Territories, which originated as colonies of the British Empire.
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