Why Britain Keeps Changing Prime Ministers

EUROPE’S POLITICAL CRISIS · BRITAIN

Britain has had six prime ministers since the 2016 Brexit vote, and the latest change shows both the revolt against the old parties and their way back.

Andy Burnham became Britain’s prime minister on 20 July 2026, after Keir Starmer resigned as Labour leader under pressure from his own MPs. He is the sixth person to take the job since the Brexit referendum of 2016, and the fifth to arrive without first winning a general election as leader.

For Americans the churn matters because Britain is Washington’s closest ally, a nuclear power and one of the world’s largest financial centres. It is also the clearest test in Europe of whether an old party can win back voters who drifted to an insurgent.

Six Prime Ministers in Ten Years

• Theresa May, 2016 to 2019 Conservative; took over after the Brexit vote.
• Boris Johnson, 2019 to 2022 Conservative; won the 2019 election.
• Liz Truss, 2022 Conservative; resigned within two months.
• Rishi Sunak, 2022 to 2024 Conservative; lost the 2024 election.
• Keir Starmer, 2024 to 2026 Labour; won the 2024 election by a landslide.
• Andy Burnham, since 20 July 2026 Labour; elected party leader unopposed.

A Landslide Built on a Third of the Vote

Labour won 411 of 650 seats in July 2024 with about a third of the vote, because Britain’s first-past-the-post system rewards the party that comes first in each seat. Reform UK won about one vote in seven but only five seats.

That gap between votes and seats fed Reform’s complaint that the system shuts out its voters. By mid-March 2026 YouGov had Reform on 25%, the Greens on 19%, and Labour and the Conservatives tied on 17%.

The May Elections and Wales

The local and devolved elections of 7 May 2026 turned the polls into seats. In Wales, where Labour had led every government since devolution in 1999, Plaid Cymru won 43 of the Senedd’s 96 seats, Reform 34 and Labour only 9.

Welsh Labour’s leader and first minister, Eluned Morgan, lost her own seat. Plaid Cymru’s Rhun ap Iorwerth became first minister at the head of a minority government.

How Starmer Fell and Burnham Rose

Burnham, who had spent nine years as mayor of Greater Manchester, won a seat in Parliament at the Makerfield by-election. On 22 June 2026 Starmer announced outside Downing Street that he would resign as Labour leader.

“I have heard the answer of my parliamentary party to that question, and I accept that answer with good grace.”Keir Starmer, Downing Street, 22 June 2026

When nominations closed in July, Burnham was the only candidate, and Labour declared him leader on 17 July. He became prime minister three days later, on 20 July 2026.

The Argument: No Mandate

Nigel Farage, Reform’s leader, demanded an immediate general election in July, saying Burnham had no mandate for power. His argument fits the wider European complaint: the establishment changes its leaders inside the party while voters who want a different party wait years for a say.

British law supports the government on the procedure. A prime minister needs the confidence of the House of Commons, not a personal election, and the next general election is due by 2029.

The Counter-Evidence: Labour’s Recovery

Since the change at the top, Labour has climbed back. YouGov had Reform and Labour tied on 22% in late July, and on 18 and 19 October Labour on 27%, the Conservatives on 23% and Reform on 22%.

In YouGov’s poll of 11 and 12 October, Reform’s 21% was its joint-lowest of this parliament. In our reading, Britain is therefore Europe’s clearest counter-example to the idea that voters, once lost to an insurgent, never come back.

The recovery is fragile, though. The three leading parties are within five points of each other, and a Pew Research Center survey this spring found 51% of Britons dissatisfied with how their democracy works.

What Prediction Markets Say

On Kalshi, regulated in the US by the Commodity Futures Trading Commission, traders give Labour a 38% chance and Reform 37% of winning the next general election, with the Conservatives on 21%. More than 261,000 contracts have been traded on that question, as of 21 October at 10:27 a.m. ET.

Why we show this: prediction markets turn real-money bets into a live probability that moves within minutes of the news, which is why investors, campaigns and newsrooms in the United States now follow them closely. We show them next to polls and official results, never instead of them.

What It Means for Americans

A stable Britain matters to Washington on defence, intelligence and trade, and frequent changes at the top make long-term deals harder. A Reform victory, which the markets now price at roughly one in three, would put an anti-immigration party in charge of a G7 economy.

For investors, political churn has already cost Britain once, when markets turned on Liz Truss’s 2022 budget plans. Any sign of fiscal drift under a new leader is watched closely in the bond market.

What Is Not Known

Nobody knows when Burnham will call an election, and he does not have to before 2029. It is also unclear whether Labour’s recovery will survive his first budget.

Britain is one of five countries in our explainer on why Europe’s politics are breaking. For the opposite approach to an insurgent party, see why Germany’s top party in the polls is kept out of power.

Frequently Asked Questions

Who is the prime minister of Britain now?

Andy Burnham of the Labour Party became prime minister on 20 July 2026. He replaced Keir Starmer, who announced on 22 June that he would resign as Labour leader.

Why did Keir Starmer resign?

His MPs withdrew their support after Labour’s heavy losses in the May 2026 elections. He said he accepted their verdict with good grace.

Did Andy Burnham win an election to become prime minister?

No general election was held. He was elected Labour leader unopposed in July, and a prime minister needs the confidence of the House of Commons, not a separate vote.

When is the next UK general election?

It must be held by 2029, and no date has been set. Reform UK’s Nigel Farage has demanded an immediate election.

Is Reform UK ahead in the polls?

Not in the latest YouGov poll. On 18 and 19 October Labour had 27%, the Conservatives 23% and Reform 22%, after Reform had led YouGov’s poll in March 2026.

More: Why Europe’s politics are breaking, our guide to the crisis from France and Spain to Germany, Romania and Britain.