On a Monday morning in late June, Keir Starmer stood outside the black door of 10 Downing Street and announced he was stepping down as both Labour leader and prime minister. After barely two years in power, he became the seventh person to hold the job in a decade—a stark reminder of how often the top job in British politics changes hands. For many voters, the flurry of resignations, leadership contests, and handovers can be confusing. But the process of a prime minister resigning is governed by a mix of constitutional convention, party rules, and simple practicality.
When a prime minister resigns, the first step is a private conversation with the monarch. Starmer, like his predecessors, called the King on 22 June 2026 to inform him of his decision. That phone call triggers a chain of events that is partly written in law and partly shaped by political tradition. The prime minister does not resign directly to Parliament, but to the head of state, who then invites the successor to form a government. The resignation is not official until the monarch accepts it.
“Explains the constitutional and party processes when a UK prime minister resigns, using Starmer's resignation as a case study.”
Once the resignation is announced, the political party in power must choose a new leader—and therefore a new prime minister. Starmer said he would remain in post until the contest is complete to ensure an orderly handover. The Labour Party’s National Executive Committee (NEC) will set the rules for the leadership election. Nominations open on 9 July and close by the start of Parliament’s summer recess. If only one candidate—such as Greater Manchester Mayor Andy Burnham—is nominated, that person could become prime minister as soon as next month. If there are multiple candidates, MPs will vote and then party members will have their say, with a new leader expected by early September, in time for the autumn party conference in Liverpool.
This system has been tested repeatedly. Since 2016, Britain has seen David Cameron, Theresa May, Boris Johnson, Liz Truss, Rishi Sunak, Keir Starmer, and now a seventh prime minister. Each resignation followed a different trigger: electoral defeat, loss of party confidence, scandal, or poor poll numbers. In Starmer’s case, the catalyst was Labour’s disastrous results in May elections and Andy Burnham’s by-election victory in Makerfield, which convinced cabinet ministers that his position was untenable.
For UK readers, these resignations can feel like a revolving door. Each change of prime minister can alter government policy on everything from the economy to foreign affairs. The Brexit reset deal that Starmer had championed—a summit with the EU scheduled for 22 July—has been postponed, leaving the agreement in limbo. Leadership contests also divert government attention from day-to-day governance, as ministers focus on internal party battles. And because the UK has no fixed election date for a change of prime minister, the public has no direct say in who becomes the next occupant of Number 10.
Q: Why does a prime minister resign to the monarch, not to Parliament? A: The UK operates under a constitutional monarchy where the prime minister is appointed by the King. Resigning to the monarch is a formal, ceremonial step that officially ends the premiership. The monarch then invites the new leader to form a government, maintaining the continuity of the state.
Q: How long does the transition take when a prime minister resigns? A: It varies. If there is an unopposed candidate, a new prime minister can be installed within days or weeks. In contested leadership races, the process can take several months. Starmer’s timetable aims for a new leader by early September, about 10 weeks after his resignation.
Q: Can the public vote for the new prime minister? A: No. When a prime minister resigns between general elections, the governing party’s internal process chooses the successor. The public only votes in a general election at a date set by the incumbent prime minister, unless a vote of no confidence forces an early election.
What happens next depends on the Labour Party’s leadership contest. Nominations open on 9 July; if Andy Burnham is the only candidate, he could become prime minister by the end of July. If multiple candidates enter, MPs will hold votes and then party members will choose the winner. The new leader and prime minister must be confirmed by early September. In the meantime, Starmer remains caretaker prime minister, handling day-to-day business. The seventh prime minister in ten years will soon step through that black door—and the cycle continues.