Andy Burnham entered Downing Street promising to end years of political instability, but the challenge facing Britain’s new prime minister extends well beyond Labour’s leadership.

Britain is moving towards an increasingly fragmented multi-party system, with traditional loyalties weakening and no party attracting the support of 30% of voters.

The latest YouGov voting-intention poll, conducted on 2 and 3 August, put Reform UK on 23%, Labour on 22% and the Conservatives on 19%. The Greens received 13% and the Liberal Democrats 12%.

A seven-poll average published by PollCheck on 6 August placed Labour ahead on 25.4%, followed by Reform on 23.6% and the Conservatives on 19.3%. The narrow gaps suggest a volatile contest rather than a decisive lead for any party.

“I know people at home are fed up with politics. I hear you. And I want to be honest with you. We have not been good enough, and we need to be better,” Burnham said in his first speech outside Downing Street on 20 July.

The former mayor of Greater Manchester returned to Parliament as the MP for Makerfield in June. He was elected Labour leader on 16 July and became prime minister four days later, succeeding Keir Starmer.

Burnham described the transfer of power as a “circuit-breaker for Britain”, promising a new economic model and a transfer of authority from Westminster to cities and regions.

He took office without a general election, as Britain’s parliamentary system allows the governing party to replace its leader while retaining its Commons majority.

That majority, won under Starmer in 2024, conceals Labour’s growing electoral vulnerability. The party secured 411 of the House of Commons’ 650 seats in that election, while the Conservatives fell to 121 in their worst result on record.

The Liberal Democrats won 72 seats, Reform five and the Green Party four.

Two years later, polling suggests that British politics is no longer defined by the contest between Labour and the Conservatives that dominated much of the previous century.

The Conservatives, led by Kemi Badenoch, are competing directly with Reform for right-leaning voters. Labour faces pressure from the Greens and Liberal Democrats, as well as regional parties in Scotland and Wales.

The shifts reflect a deeper crisis of confidence identified by More in Common, a research organisation established in memory of Labour MP Jo Cox, who was murdered in 2016.

Its study of more than 20,000 people found that 87% of Britons had little or no trust in politicians, while seven in 10 believed the country was heading in the wrong direction.

Money was the biggest source of stress for 43% of respondents, and half believed the cost-of-living crisis would never end. The research concluded that Britain’s divisions could no longer be adequately understood through a simple left-right divide.

The present upheaval has roots in economic and social changes stretching back decades.

Margaret Thatcher’s governments transformed the relationship between the state, organised labour and private ownership after she entered office in 1979. Privatisation, restrictions on trade unions and the Right to Buy housing programme reshaped the economy and the political loyalties of working-class voters.

Tony Blair later moved Labour towards the political centre under the banner of New Labour, returning the party to power in 1997 after four consecutive general election defeats.

Blair retained much of the economic system he inherited but introduced a national minimum wage, increased health spending and supported the transfer of powers to Scotland and Wales. His government also helped negotiate the 1998 Good Friday Agreement in Northern Ireland.

The 2016 referendum on European Union membership disrupted the electoral coalitions within both major parties. Britain formally left the EU on 31 January 2020 and withdrew from the single market and customs union at the end of that year.

The Office for Budget Responsibility estimates that Brexit will leave UK productivity and gross domestic product about 4% lower in the long term than they would have been had the country remained in the EU.

That is an estimate based on a hypothetical alternative rather than a direct measurement. The economic consequences of Brexit are difficult to separate from the effects of the Covid-19 pandemic, the war in Ukraine and disruptions to global supply chains.

The latest trade figures present a mixed picture. The EU accounted for 41% of UK exports and half of its imports in 2025.

UK goods exports to the EU were 14% below their 2019 level in real terms, while services exports were 28% higher.

Translating today’s voting-intention figures into parliamentary seats is particularly uncertain because Britain elects MPs through the first-past-the-post system. National vote shares do not produce a proportionate distribution of seats.

Using polling data available through 29 July, PollCheck projected Labour as the largest party with 265 seats, followed by Reform on 129, the Conservatives on 98 and the Liberal Democrats on 70.

Labour would still be 61 seats short of the 326 required for a Commons majority. The figures are a modelling exercise rather than an election prediction, and small changes in geographically concentrated support could produce markedly different results.

Reform leader Nigel Farage faces a more immediate electoral test. He resigned as the MP for Clacton on 8 July to trigger a by-election, before announcing that he would contest the seat again.

Farage said he wanted his constituents to judge allegations concerning whether he properly disclosed gifts from wealthy supporters. He has denied wrongdoing and accused what he called the political establishment of trying to discredit him.

The Clacton by-election will be held on 13 August. Unless Burnham requests an earlier dissolution of Parliament, 15 August 2029 is the last possible date for Britain’s next general election.