Last Word: The Political Legacy of Brexit

Maria Sobolewska explores how Brexit weakened both major parties and ushered in a new era of political fragmentation.

Ten years ago, Brexit was supposed to settle an argument. Instead, it detonated one. A decade on from the referendum, Britain’s political landscape is critically fractured. Reform now threatens the Conservatives from the right. Labour is losing support to rivals on its left.

Brexit’s impact on politics can be felt in three main ways. The first is how it reshaped the space of political competition. The second is what it did to the fortunes of the Labour and Conservative parties. The third is the fragmentation of the party system. The big question is: what happens next?

In terms of political competition, it is almost as though the referendum settled nothing. The decision to leave the EU did not resolve the social conflicts or political grievances that led to that fateful vote. Instead, it brought them out into the open.

The main reason is that one of the central conflicts underpinning Brexit concerned globalisation and its costs: from the symbolic question of control over laws and the economy to the thorny issue of immigration. These are not problems that any single government can easily solve. Immigration illustrates this particularly well. In the absence of any viable policy solution to stop immigration, and given the basic economic reality that Britain depends on immigrant labour, this issue is likely to remain politically salient for decades to come.

Labour and the Conservatives are no better placed to absorb these conflicts than they were before the referendum. Now sitting second and third in Westminster voting-intention polls, and emerging as the two biggest losers from the 2026 local elections, both parties have clearly failed to recover from the Brexit shock. Yet they have done so for opposite reasons.

The early signs of the Conservative Party’s successful realignment around Brexit now seem long gone. Most likely, this is because Brexit itself was an expression of those unresolved conflicts over globalisation. The party was able to raise voters’ hopes in 2019 that leaving the EU would address them. When that failed to happen, the underlying pressures simply returned.

The Conservatives were no better placed to solve these problems than they had been before the referendum. Despite ending EU freedom of movement, demand for immigrant labour was largely met through migration from outside the EU. Nor were the Conservatives better able to deliver on bread-and-butter issues. Brexit left the British economy weaker, limiting the government’s room for manoeuvre. Unable to resolve the issues that fuelled Brexit in the first place, the Conservative Party could not indefinitely remain the party of Brexit.

Labour’s inability to absorb Brexit-related conflicts stems from a different problem. Labour never wanted to become a party of Remain. This strategy brought shortterm rewards. The 2017 General Election appeared to show that what Rob Ford and I called ‘Brexit Blairism’ could deliver additional votes and seats.

However, the Conservatives’ repositioning and Labour’s relative immobility produced a one-sided realignment over Brexit that proved unsustainable.

These opposite strategies each delivered a period of success – first for the Conservatives and then, in 2024, for Labour. Yet both successes contained the seeds of future difficulties. By pivoting and failing to deliver, in the Conservatives’ case, and by failing to pivot, in Labour’s, each party exposed its flank on one side of the political spectrum. Both effectively allowed the same half of the electorate to shape their political agenda. It is like watching two football teams playing towards the same goal on the same half of the pitch. The problem is that it leaves the other half of the pitch undefended.

This helps explain the third major consequence of Brexit: party fragmentation.

Voters increasingly choose between blocs of parties rather than between two dominant competitors. It is unsurprising that fragmentation is greater on the left, where Labour has left its flank particularly exposed. Left-leaning voters who no longer wish to support Labour can choose from the Liberal Democrats, Greens, or the nationalist parties of Scotland and Wales. On the right, alongside the Conservatives, stands Reform – a party empowered both by its leader’s role in the referendum campaign and by the Conservatives’ failure to deliver the promised benefits of Brexit.

The biggest unknown, and perhaps the most significant long-term consequence of Brexit, is whether this fragmentation will ultimately lead to the replacement of one of the major parties or to the adoption of proportional representation (PR).

A Reform victory and the subsequent demotion of the Conservatives is certainly conceivable. It would mirror the replacement of the Liberals by Labour in the 1920s. Britain’s electoral system discourages the rise of new parties and the collapse of old ones – until, suddenly, it does not. The Liberals lost their status as one of Britain’s two main parties in the space of a single election.

For students of politics, this is undoubtedly the most exciting scenario. Yet efforts to prevent such an outcome may prompt politicians to revive the previously abandoned cause of PR. By institutionalising fragmentation, they could guarantee the survival of parties that have become considerably diminished versions of their former selves.

Ten years on, Brexit’s most important legacy may not be Britain’s relationship with Europe at all. It may be the transformation of the party system that has governed British politics for more than a century.