Prime Minister of the United Kingdom

The prime minister of the United Kingdom is the head of government of the United Kingdom. The prime minister advises the sovereign on the exercise of much of the royal prerogative, chairs the Cabinet, and selects its ministers. Modern prime ministers hold office by virtue of their ability to command the confidence of the House of Commons, so they are invariably members of Parliament.

The office of prime minister is not established by any statute or constitutional document, but exists only by long-established convention, whereby the monarch appoints as prime minister the person most likely to command the confidence of the House of Commons. In practice, this is the leader of the political party that holds the largest number of seats in the Commons. The prime minister is ex officio also First Lord of the Treasury (an office often associated with the premiership between 1721 and 1895, after 1902 always united to it, and, after 1905, an official title of the position), Minister for the Civil Service, the minister responsible for national security, and Minister for the Union. The prime minister's official residence and office is 10 Downing Street in London.

Early conceptions of the office of prime minister evolved as the primus inter pares ("first among equals"); however that does not differentiate on status and responsibility upon whoever is holding office. Historically, the prime minister was the first amongst equals, until 1868. Since then, that characterisation of the prime minister has changed to be reflective of the democratic nature of their position, but also their heightened importance. The power of the prime minister depends on the support of their respective party and on the popular mandate. The appointment of cabinet ministers and granting of honours are done through the prime minister's power of appointment. The prime minister alongside the cabinet proposes new legislation and decides on key policies that fit their agenda which are then passed by an act of parliament.

The power of the office of prime minister has grown significantly since the first prime minister, Robert Walpole in 1721. Prime ministerial power evolved gradually alongside the office itself which have played an increasingly prominent role in British politics since the early 20th century. During the premierships of Margaret Thatcher and Tony Blair, prime ministerial power expanded substantially, and their leaderships in the office were described as "presidential" due to their personal wielding of power and tight control over the cabinet. The prime minister is one of the world's most powerful political leaders in modern times. As the leader of the world's sixth largest economy, the prime minister holds significant domestic and international leadership, being the leader of a prominent member state of NATO, the G7 and G20.

As of 2025, 58 people (55 men and 3 women) have served as prime minister, the first of whom was Robert Walpole taking office on 3 April 1721. The longest-serving prime minister was also Walpole, who served over 20 years, and the shortest-serving was Liz Truss, who served seven weeks. Keir Starmer succeeded Rishi Sunak as prime minister on 5 July 2024, following the 2024 general election.

History

Origins: 1689–1742

The position of prime minister was not created but evolved slowly and organically over three hundred years due to numerous Acts of Parliament, political developments, and accidents of history. Therefore, the office is rarely found in any statute and according to the Political and Constitutional Reform Committee in 2014: "It is impossible to point to a single point in history when the post was created or even a decision to create it."

The 17th century saw a transformative period in British history. The Union of the Scottish and English crowns followed by the Wars of the Three Kingdoms, including the English Civil War, saw the final conflict between the Monarchy and the parliaments (of England and Scotland) over governance, culminating in the end of absolute monarchy with the execution of Charles I in 1649. In 1660, the Monarchy was restored with the ascension of Charles II signalling a return to royal rule but with growing limitations. The Glorious Revolution of 1688–1689 led to the deposition of the Catholic James II and the establishment of William III and Mary II as constitutional monarchs. After a series of bills passed by the parliaments, such as the Bill of Rights and Claim of Right in 1689, the powers of the monarch were reduced, being replaced by the powers of parliament. The Bill of Rights established the supremacy of Parliament over the Crown and set up certain civil rights. During this period, Parliaments were dominated by two political factions: the Whigs and the Tories. The Whigs supported parliamentary sovereignty and constitutional monarchy while the Tories favoured the divine right of kings and the deposed James II. These two groups were considered by some to be "embryonic political parties."

The resulting English Constitution established in 1689 gave the English Parliament the power over the "purse" or the Treasury. The monarch who now could commit to and follow agreed policy allowed Parliament to pursue and fund its own policies without any fear of diversion of the funds. By this point, the Monarch was forced by incentive to cede power to Parliament under the credible threat of removal of any who ignored the Constitution.

Acts of Union in 1707 formed the Kingdom of Great Britain, with the Parliament of Great Britain the head of Treasury, as Lord Treasurer, was given the power following Standing Order Number 66 to draft money bills (budgets) instead of MPs outside of government. The informal term 'prime minister' was first recorded around that time, which since 1721 had mostly also been the office holder for the First Lord of the Treasury. The First Lord of the Treasury is one of the Lords Commissioners of the Treasury. This role is usually held by the prime minister. The role of prime minister grew more distinct as the head of government and often more recognisable within the public than other members of the cabinet, which demonstrates the increasing power of the prime minister in modern times than that originally created.

Following the death of Queen Anne in 1714, Parliament invited George Louis, Prince Elector of Hanover, to become king. During his reign, he was unpopular partly due to his limited English proficiency and lack of interest in governing, a role he largely left to his ministers. In 1720, the South Sea bubble, a financial crisis stemming from speculative investments, led to economic turmoil. The collapse implicated many government officials. With schisms within the Whigs Party led to the fall of Stanhope–Sunderland ministry. Subsequently, Sir Robert Walpole, who was serving as Paymaster of the Forces, was appointed First Lord of the Treasury in 1721. Sir Robert Walpole was the first prime minister of the United Kingdom, though his predecessors as First Lord of the Treasury also held a similar position. Walpole is considered the first "de facto prime minister" due to his influence over policy and control of government affairs. He was not, in the modern sense, "prime minister". This was due to the position being not formally recognised by any legal fixture and also due to the position originally being used as a term of abuse.

Walpole served as prime minister from 1721 to 1742. The time during his premiership was dubbed by historians as the "Robinocracy". His financial abilities in handling the repercussions in the aftermath of the South Sea Bubble earned him the support of commercial and landed interests, pursued a largely peaceful foreign policy, lowered taxes and reduced national debt while his skilful management of Commons affairs solidified his dominance in Parliament by operating as a "Screen-Master General", pulling strings and sullying favour whenever necessary. Walpole's policy was to maintain the status quo and despite not passing any major reforms, Walpole provided the country with much-needed stability after a century of turmoil. His time in office was crucial in shifting political power to the House of Commons and laying the foundations for the modern Cabinet system. Despite being able to successfully hold power for 20 years, Walpole faced fierce opposition over alleged bribery and corruption in Parliament and following a disastrous war with Spain, he resigned in 1742 and was succeeded by the Earl of Wilmington.

Development: 1742–1945

Following the resignation of Walpole, a swift string of ministries followed and between 1742 and 1760 there were five separate governments. Spencer Compton, Earl of Wilmington was made prime minister. However, Wilmington served for a brief time and was head of government by name only. The government continued to be dominated by internal struggles over Britain's participation in the War of the Austrian Succession and royal intervention in policy making. In 1743, Henry Pelham became prime minister and sought to expel ministers, particularly Lord Carteret, who sought to undermine the authority of the new ministry.