Politics 101: How the British Government Works

The United Kingdom has never written its constitution down. What is known as the "British Constitution" is instead a patchwork of statutes, court rulings, and unwritten convention accumulated over roughly a thousand years, alterable at any time through an ordinary act of Parliament rather than a formal amendment process.

British history stretches back to the Iron Age, with partial Roman conquest in 56 CE and England, Scotland, Wales, and Ireland taking shape by the 800s. The Norman Invasion of 1066 marks the conventional starting point for British political history, but the legal foundations were laid in 1215, when Magna Carta forced King John to concede rights to the barons and nobles underpinning the kingdom's administration. It fell far short of democracy, but it was among the first formal limits imposed on a European monarch, including a clause that would resonate centuries later on the other side of the Atlantic: no taxation without representation. A king seeking to wage war required the "consent of the realm," at first through a council of barons that evolved over the following centuries into Parliament.

The 150 years between 1550 and 1700 brought wholesale change. England, Scotland, and Ireland's split from the Catholic Church was settled with comparatively little of the religious warfare seen elsewhere in Europe. In 1649, at the close of the English Civil War, Parliament executed King Charles I for treason, a crime that had previously been understood to run only in the other direction, against the king. Parliament then governed directly during the Protectorate, demonstrating that monarchy was not the only viable form of government, though the monarchy was restored under Charles II in 1660. The Glorious Revolution of 1688, in which Parliament invited a Protestant claimant to replace the fleeing James II, cemented Parliament's supremacy: it was now Parliament, not hereditary succession alone, that determined who wore the crown, and the divine right of kings was at an end.

England and Scotland formally merged in 1701, and the crown subsequently passed to George I of the German House of Hanover, who spoke no English and relied on a single minister to manage affairs of state, a "prime" minister. Robert Walpole is generally regarded as the first, de facto holder of that office. Unlike the United States or France, Britain's transition away from absolute monarchy did not come through a single revolution that reordered the state; it came through five centuries of incremental concession, each surrender of royal power formalizing what had already shifted informally. The result is the British Constitution: an accumulation, built over roughly 811 years, that functioned as a pressure valve releasing the tensions that produced sharper ruptures elsewhere in Europe. Britain avoided the revolutionary wave of 1848 and went on to preside over a global empire for the following century, an empire that ultimately collapsed under its own weight as public sentiment shifted and the costs of the Second World War made maintaining colonial holdings across Africa, Asia, and the Caribbean untenable.

Constitutionally, the United Kingdom remains a constitutional monarchy. The monarch, currently Charles III, is the hereditary head of state; he acceded following the death of his mother, Elizabeth II, in 2022, with the Prince of Wales, William, next in line, followed by his son George. The monarch is nominally the government: he invites the leader of the winning party to form a government in his name, the military swears allegiance to him, and his image appears on the currency. He cannot be charged with a crime and holds the formal power to dissolve Parliament or withhold royal assent from legislation, powers no modern monarch has exercised. The last monarch to dissolve Parliament unilaterally was William IV in 1834; the last to veto a bill was Queen Anne in 1702. Monarchs since have understood the political cost of testing those limits and have confined themselves to ceremonial functions, private counsel, and public engagements.

Real executive authority resides in Parliament, and its head, the Prime Minister, holds no formally defined qualifications; the office belongs by convention to whoever can command a majority in the House of Commons, which in practice means the leader of the largest party, who must themselves be an elected Member of Parliament. There is no separate national election for the premiership: the position passes automatically to the leader of the winning party, or to whoever can assemble a coalition. The Prime Minister's authority over foreign and domestic policy is broadly comparable in scope to a president's, but with an added constraint a president does not face: the Prime Minister must retain the confidence of their own party as well as the electorate, and British parties have increasingly been willing to remove sitting Prime Ministers mid-term. Once appointed by the monarch, the Prime Minister names the heads of government departments without any confirmation process; ministers simply take up their posts. This reflects the UK's status as a purely parliamentary system in which Parliament, and by extension the governing party, holds essentially all formal power.

Parliament itself is bicameral. The House of Lords, its upper chamber, has roughly 800 members appointed effectively at the government's discretion rather than elected or tied to any constituency. Hereditary peers, who inherited their seats, existed until reforms introduced this year by the then Prime Minister, Keir Starmer, modernized the chamber; most remaining members are senior party figures granted a peerage as a capstone to their careers, tasked with reviewing legislation from the lower house. The House of Commons, by contrast, is where the substantial majority of governance occurs and from which the Prime Minister and most ministers are drawn. In the absence of a codified constitution, Parliament's authority is close to unlimited: it can pass essentially any law, a principle known as parliamentary sovereignty that came under particular strain during the Brexit process, when Parliament retained the legal power to disregard the referendum result even though doing so would have been politically untenable.

Members of the Commons are elected from 650 single-member constituencies under First Past the Post, with no majority threshold and no runoff. MPs are not required to live in the constituencies they represent, and residency is not formally tracked, a gap that has periodically become a political liability. The system functions cleanly when two parties dominate, which was the historical norm as competition ran between the Conservatives and, later, Labour, with the winning candidate typically approaching fifty percent of the vote. As smaller parties on the left, such as the Greens, and the right, such as Reform UK, have drawn support away from the two establishment parties, the system's disproportionality has become more pronounced. The 2024 general election was the starkest illustration to date: Labour won 411 seats, 63 percent of the Commons, on just under 34 percent of the national vote, the lowest vote share ever recorded for a single-party majority government and, by the Gallagher index, the most disproportionate outcome in British electoral history.

There is no judicial review in the American or continental European sense, a direct consequence of the absence of a written constitution. The UK Supreme Court, established only in 2009, serves as the final court of appeal for civil cases across the UK and for criminal cases in England, Wales, and Northern Ireland. Its twelve justices are appointed by an independent commission with input from the Lord Chancellor, the UK's roughly equivalent office to the US Attorney General. Unlike France's Conseil Constitutionnel, Germany's Constitutional Court, or the US Supreme Court, the UK Supreme Court cannot strike down an act of Parliament; it can interpret legislation and issue a declaration that a law is incompatible with human rights protections, but Parliament remains free to disregard that declaration. Nor is there a single unified legal system: England and Wales share a court structure, while Scotland and Northern Ireland each maintain their own, separate systems.

Since the late 1990s, the UK has devolved significant authority, over health, education, and policing among other areas, to Scotland, Wales, and Northern Ireland, each governed by its own parliament or assembly and First Minister, elected by proportional representation rather than First Past the Post. England alone has no devolved parliament and is governed directly from Westminster, meaning Britain currently runs two distinct electoral systems depending on which layer of government is being elected. This arrangement, generally termed the Westminster system, has been exported to many of Britain's former colonies and dominions, from Australia to Trinidad and Tobago to India, the world's largest democracy by population. Canada follows a similar model, sharing the same monarch as head of state, a Prime Minister who governs only with the confidence of the Commons, and an appointed upper chamber, the Senate, closer in function to the House of Lords than to the US Senate. Canada diverges from Britain in one significant respect, however: it layers this Westminster machinery onto genuine federalism, with ten provinces holding constitutionally guaranteed powers more comparable to Germany's Länder than to Britain's devolved nations.

The United Kingdom is not a member of the European Union.

Responsibility within the British system follows accordingly. National law, foreign policy, and the economy fall to the Prime Minister and whichever party controls the Commons. Policy on schools or hospitals in Scotland, Wales, or Northern Ireland is the responsibility of the relevant devolved government, not Westminster or the monarch. A seat allocation that diverges sharply from the national vote share reflects First Past the Post functioning as designed, rewarding concentrated support over support that is spread thinly across constituencies. And because no written constitution constrains Parliament, a law that infringes on a right is checked only by the political cost of doing so, a cost every Prime Minister has had to weigh.