The United Kingdom is a parliamentary democracy: the government arises from the majority in the House of Commons and depends on it. The system, known as the Westminster model and copied by dozens of countries, took shape slowly over the centuries, from Magna Carta in 1215 to the Glorious Revolution of 1688, and does not rest on a constitution written in a single document, but on fundamental statutes, court rulings, treaties and above all established conventions.
Parliament
The Westminster Parliament, which meets in the Palace of Westminster in London (see the Palace of Westminster), has three elements: the sovereign, the House of Lords and the House of Commons.
- The House of Commons is the heart of the system. It has 650 Members of Parliament (MPs), each elected in a single-member constituency under the first past the post system: whoever gets the most votes wins, even without an absolute majority. A Parliament lasts at most five years. The Commons votes on laws, the budget and confidence in the government.
- The House of Lords is an unelected chamber of more than eight hundred members: mostly life peers appointed by the sovereign on the recommendation of the parties and an independent commission, plus 26 bishops of the Church of England. In 2026 the House of Lords (Hereditary Peers) Act abolished the last seats reserved for hereditary peers, present for more than seven hundred years. The Lords scrutinise and amend laws, but can only delay them, not block them.
The majoritarian system usually produces large majorities on relatively low shares of the vote: in 2024 the Labour Party won almost two thirds of the seats with about 34% of the vote, while Reform UK, with more than 14%, got only five MPs.
The government
The Prime Minister is the leader of the party that controls a majority in the Commons; he is appointed by the King and lives at 10 Downing Street. He chooses the ministers of the Cabinet, including the Chancellor of the Exchequer (finance), the Foreign Secretary and the Home Secretary. Ministers must be members of Parliament. Because the Prime Minister depends on his party, he can be replaced without a new election: this has happened several times in recent years, most recently in July 2026, when Keir Starmer resigned and the Labour Party chose Andy Burnham as its new leader, who had returned to Parliament at a by-election a few weeks earlier. The largest minority party forms the Official Opposition, with its own "shadow cabinet". See the list of prime ministers.
The parties
British politics was dominated for a century by two parties, the Conservatives (Tories) and Labour, with the Liberal Democrats as the third force. In recent years the system has fragmented: Reform UK, a populist anti-immigration party led by Nigel Farage, has grown, doing very well in the 2025 and 2026 local elections, and the Greens have risen; in Scotland, Wales and Northern Ireland the national parties matter most, such as the SNP, Plaid Cymru, Sinn Féin and the DUP.
Devolution
Since 1999 many powers have been transferred to the parliaments of Scotland (Holyrood, 129 members), Wales (the Senedd, 96 members from 2026) and Northern Ireland (Stormont, 90 members), which have their own governments. Westminster keeps foreign policy, defence, currency, immigration and most taxation. In England, which has no parliament of its own, power has been partly devolved to elected metro mayors. See Scotland, Wales and Northern Ireland.
Justice
The judiciary is independent. Since 2009 the court of last resort has been the Supreme Court of the United Kingdom, which sits opposite Parliament; previously this role belonged to a committee of the House of Lords. England and Wales, Scotland and Northern Ireland have separate legal systems: see the English legal system and the Scottish legal system.