Andy Burnham is the UK’s seventh prime minister (PM) in 10 years, prompting journalists and commentators to talk of a ‘revolving door’ at No.10, ‘prime ministerial churn’ and the country ‘burning through’ its PMs at an alarming rate. Three prime ministers during this period – David Cameron, Boris Johnson and Keir Starmer all resigned within 3 years of securing a parliamentary majority. When set against recent decades, the years 2016-26 are unique in modern British political history because of the rate at which prime ministers have come and gone. Indeed, over this period the UK has had more national leaders than most developed countries. The tables below illustrate these points in more detail.

Many factors have been put forward to explain the ‘revolving door’ premiership since 2016 but, of these, (1) Brexit (2) individual mistakes and failings (3) economic problems, and (4) growing MP dissent and rebelliousness have all played an important role.

Brexit

The Brexit campaign and referendum of 2016, which cut across existing political divisions and created new ones with the Leave-Remain fault line, has made the PM’s job harder and more precarious by introducing greater political instability in three key ways.

First, in the years before Brexit, the electorate had become more volatile and less aligned with the traditional parties. As old party loyalties eroded, voters have been more willing to opt for other parties. The Brexit referendum, however, gave significant momentum to this process by introducing a new Leave-Remain division which cut across existing political identities and affiliations. Thus, a major political consequence of the Brexit referendum was to divide the Labour and Conservative tribes internally, making it much more difficult for PMs to build stable and lasting coalitions of support, shortening political honeymoons for incoming premiers and prompting the earlier appearance of significant voter dissatisfaction with PMs. Labour voters split roughly 70% to 30% in favour of remaining within the EU. Within Labour’s ranks, professionals and younger university-educated workers living in big cities voted overwhelmingly to remain but many Labour working-class voters in the post-industrial parts of northern England and the Midlands opted to leave. Among Conservatives, 58% voted to leave and 42% chose to remain. Tory Remainers tended to be professionals and graduate workers from urban and suburban areas whereas their Leave counterparts were mainly older, school-educated workers or retirees from the C2DE occupational groups. Generally speaking, Remainers attached to both parties supported social liberal values such as freedom of movement, internationalism and economic integration. Tory and Labour Leavers backed socially authoritarian or traditional values, calling for enhanced national sovereignty and stricter immigration controls.

Second, the Brexit process exacerbated tensions and conflicts within the parliamentary parties, particularly the Conservatives, and created a heightened culture of rebellion and dissent which has often weakened the PM’s standing. Under Therea May’s premiership, for example, numerous rebellions over the Withdrawal Agreement exposed the Leave-Remain differences among Tory MPs and undermined her authority as PM.

Finally, the difficult and disappointing results of Brexit after 2016 have left both Leavers and Remainers with a deep sense of disillusionment regarding the political establishment. Around 60% of the electorate now think the UK was wrong to leave the EU (including almost 25% of Leave voters) and 61% consider Brexit more of a failure than a success. Many Leavers complain that Brexit has not delivered the expected political and economic benefits and most Remainers see the UK as weaker outside the EU. In this way, Brexit has fuelled the voter dissatisfaction and distrust that has contributed to political fragmentation and polarization, the rise of populist challenger parties and the growing difficulties PMs face in retaining sufficient public support from a deeply divided electorate.

Individual mistakes and failings

The rapid turnover of prime ministers can also be explained to some extent by the fact that some of them made major miscalculations or demonstrated serious failings. Cameron’s controversial decision to call the Brexit referendum and campaign publicly for Remain was a high stakes gamble because it carried with it the danger that he would lose all political credibility and capital if the Leave campaign won. The result completely undermined his premiership and he resigned immediately afterwards. Theresa May, as discussed above, was also a casualty of Brexit but she certainly did not help her cause by calling a surprise general election in 2017 which starkly exposed her inability to campaign effectively and resulted in the Tories losing their parliamentary majority. Johnson’s cavalier attitude to the truth, rules and standards were clearly demonstrated in the Owen Paterson lobbying affair, the ‘Partygate’ scandal and ‘Pinchergate’. Following the earlier confidence-sapping episodes, the Chris Pincher affair triggered 62 government resignations, an exodus which forced Johnson to resign in July 2022. Liz Truss’s short-lived premiership imploded due to her badly conceived ‘mini-budget’ of September 2022 which caused turmoil in the financial markets, sent the pound to a record low against the US dollar and compelled the Bank of England to intervene to shore up the bond market, protect pension funds and prevent a wider economic crisis. Rishi Sunak, the third Tory PM since 2019, failed to convince the electorate that he was the political leader who would break away from a 30-year-old ‘political system that incentivizes the easy decision, not the right one’ and could only deliver one of his 5 key pledges (to halve inflation) by the time of the 2024 general election. Keir Starmer was dragged down by his inability to offer the electorate an engaging and compelling vision of the UK’s future under his premiership and some serious political misjudgements, notably the decision to appoint Peter Mandelson as the UK ambassador to the US.

Economic problems

All six PMs who have come and gone since 2016 struggled with the negative political impact caused by serious economic and fiscal problems. After the 2008 global financial crisis, the Conservative-led coalition government (2010-15) under Cameron responded with severe ‘austerity’ public spending cuts (affecting services such as the NHS and the welfare system) which exacerbated generational and regional inequality. This was followed by the economic fallout from Brexit which post-2016 lowered investment, raised costs and reduced the UK’s annual GDP. In addition, since 2008, the UK economy has been plagued by low productivity and shrinking real terms incomes for British workers. Furthermore, massive government emergency spending during the Covid pandemic and extensive energy subsidies following Putin’s invasion of Ukraine (2022) raised UK national debt to over 100% of GDP by the early 2020s. On top of this, Truss’s unfunded tax-cutting ‘mini-budget’ in 2022 spooked the bond markets and raised the cost of borrowing for those with mortgages. Finally, the post-Covid rise in inflation led the Bank of England to maintain high interest rates which increased the government’s debt-servicing costs, leaving little money for tax cuts (when the overall tax burden was at its highest since the late 1940s) or investment in public services. As a result, since 2016, successive PMs have found it virtually impossible to sustain popular support because economic stagnation, low growth and high debt have prevented any significant improvement in living standards or public services for voters, resulting in ongoing popular frustration with the UK’s political leadership and greater electoral volatility.

The rise in rebelliousness among MPs

Since 2016, MPs have become more prepared to rebel against their parliamentary leaders, leading to a decline in party loyalty which provides the essential support framework for the PM. The Brexit referendum created Leave and Remain ideological factions within the Tories and Labour which overrode traditional partisan attachments and encouraged dissent, rebellions (or the threat of rebellions) and temporary cross-party alliances to thwart unpopular prime ministerial initiatives. In 2019, for example, 118 Conservative MPs voted against Theresa May’s Withdrawal Act, thereby demonstrating that such rebellions had the power to block the executive’s policy. Starmer was forced to change his proposed welfare reforms in 2025 when faced with the prospect of a rebellion by 126 Labour backbenchers. Moreover, with change at the very top happening more often over the last decade, the usual disadvantages associated with parliamentary rebellion for government backbenchers (such as the loss of promotion prospects) now carry much less weight and the potential leverage over the PM derived from such actions has increased. In recent years too, digital technology, notably the WhatsApp social media platform, has enabled parliamentary party factions such as the Conservative European Research Group to organize privately and largely circumvent the whips and other forms of traditional party discipline. Furthermore, partly due to technology, MPs are now much more sensitive to constituency feedback and when faced with a choice of either supporting an unpopular government policy or protecting their own seat by refusing to endorse the executive’s measure, government backbenchers have increasingly opted for electoral survival rather than party loyalty or loyalty to the PM.