News analysis: 6 PMs in a decade – Why is the United Kingdom stuck in political turmoil?

UK Prime Minister Keir Starmer announced his resignation on Monday, saying a successor is expected to take office by September.

His departure marks the latest chapter in a decade of political instability that has unfolded since Britain's 2016 Brexit referendum. Over the past 10 years, the UK has cycled through six prime ministers: David Cameron, Theresa May, Boris Johnson, Liz Truss, Rishi Sunak and Starmer.

Among them, Johnson served the longest, remaining in office for just over three years, while Truss lasted only 49 days before being forced out after her government's sweeping tax-cut package triggered turmoil in financial markets.

When Starmer led the Labor Party to a landslide victory in the 2024 general election, he promised to help heal Britain's divisions and revive its economy. Yet less than two years later, his popularity had plummeted as voters grew increasingly frustrated with stagnant living standards and a lack of visible progress on key economic issues. Facing mounting pressure from within his own party, Starmer ultimately announced resignation.

Brexit reshaped Britain's political landscape

Analysts say the rapid turnover of prime ministers reflects deeper structural changes in British politics triggered by Brexit, including the rise of populism, increasing political polarization and persistent economic headwinds.

Wang Zhanpeng, director of the British Studies Center at Beijing Foreign Studies University, told CGTN that Britain's electoral system has traditionally been conducive to producing stable governments, making minority administrations and coalition governments relatively uncommon.

"Brexit, however, fundamentally altered Britain's political ecosystem," Wang said. "Public trust in the two traditional major parties has steadily eroded, while the broader rise of populism across the West has accelerated fragmentation within the British party system and affected economic development."

According to Wang, parties such as UK Independence Party (UKIP), the Brexit Party and later Reform UK emerged during and after the Brexit process as influential voices on the political right, reshaping Britain's traditional political landscape.

"At the same time, British party politics has become increasingly election-driven," he said. "Political parties have focused excessively on winning elections, often at the expense of long-term governance, resulting in frequent changes of leadership and reduced political stability."

Deepened fragmentation and polarization

Over the past decade, Britain's political fragmentation has become increasingly entrenched.

According to Wang, before Brexit, both the center-right Conservative Party and the center-left Labor Party largely competed for voters in the political center. However, the Brexit process accelerated the rise of populist and anti-establishment forces. Reform UK, in particular, has steadily expanded its support base, challenging the Conservatives' traditional dominance on the right and, according to recent polls, emerging as one of the country's most popular political parties.

Labor has faced its own challenges. While Starmer sought to maintain a centrist course, his government struggled to deliver tangible results and faced growing internal divisions. Meanwhile, smaller parties, including the Green Party and the Liberal Democrats, have continued to attract support, further splintering the electorate.

Under Britain's parliamentary system, governments depend on securing and maintaining majority support in Parliament. As votes become increasingly dispersed among multiple parties, governing majorities have become more fragile.

"It is becoming harder for any party to occupy the political center and build broad-based consensus," Wang said. "The expansion of support at both ends of the political spectrum is driving a political realignment and that represents the most significant transformations in UK politics today."

Economic pressures undermine governments

The UK's economic difficulties have also contributed to its political volatility.

Successive governments have had to grapple with a series of challenges, including higher trade costs after Brexit, chronic fiscal pressures, strains on the National Health Service (NHS), weak productivity growth, inflation and elevated interest rates.

None of these problems could realistically be resolved within a single parliamentary term. Yet, after years of economic stagnation, public patience has worn thin.

Wang said Starmer's resignation reflected both a fragile political foundation and his inability to deliver on key promises.

"Starmer pledged to lead a national renewal, but that goal remained largely unfulfilled," he said. "Economic growth was weak, the cost-of-living crisis persisted, and several policy reversals damaged public confidence. The Labor Party's poor performance in local elections this May ultimately became the tipping point."

Can Britain move beyond Brexit?

For many economists, Brexit remains a central factor behind Britain's long-term economic challenges.

Jonathan Portes, a professor of Economics and Public Policy at the School of Politics & Economics of King's College London, told China Media Group in a recent interview that Brexit had significantly damaged the British economy. He said the UK economy is "smaller and weaker" than it would have been had Brexit not occurred.

At the same time, he argued that the European Union (EU) also suffered from Britain's departure. Closer cooperation between the UK and the EU could strengthen both sides as they confront mounting economic, geopolitical and security challenges.

Britain's official budget forecasters estimates suggest that, 15 years after Brexit, the British economy could be around 4% smaller than it would have been had the country remained in the EU. Some economists project an even greater impact, estimating a reduction of 6% to 8%, while investment – one of the key drivers of economic growth – could fall by as much as 18%.

A decade after Brexit, Britain remains far from overcoming the divisions unleashed by the referendum. The country's political debates now extend beyond the traditional left-right divide to encompass issues ranging from relations with Europe and immigration to climate policy, public services and national identity.

Whoever succeeds Starmer will face the difficult task of navigating these competing demands while restoring economic growth, improving government effectiveness and rebuilding public trust. Whether Britain's next leader can finally turn the page on the Brexit era remains an open question.