The structural shifts brought about by Brexit dismantled Labour's base.
The argument
This argument explains the 2019 result as the collapse of a coalition rather than as a failure of campaigning. The Labour Party's strength stemmed from the alignment of the working-class with university-educated middle-class voters. Both groups came under the Labour banner because their economic interests aligned: both wanted higher wages, stronger trade unions, quality and accessible public education, and a world-class health system free at the point of use. The alliance was never one of shared identity or culture, which is why the argument treats it as contingent — it held only so long as the same policies served both groups. Brexit, on this reading, created a seismic jolt in British politics, and the jolt pushed the economic interests of these two key demographics out of alignment. Once the central question became Brexit itself, the two halves of the coalition were being asked about different things, and no position on that question could serve both. The divergence was visible before the vote. In the run-up to the 2016 referendum there were already warning signs: the economic interests of the working-class had moved to immigration, while the middle-class maintained their focus on wages, free trade and the free movement of people. Those are not merely different priorities but opposed ones, since the free movement the middle-class valued was the immigration the working-class had come to see as an economic threat. The 2019 election was the result of these two core groups of Labour supporters falling out of alignment, with working-class voters flocking to the Conservatives over concerns that their economic interests were not being heard in Jeremy Corbyn's Labour Party. Unless it radically changed the core focus of the party, Labour was always doomed to lose that election — the defeat was structural rather than incidental.
Context
Labour has only been a potent force in UK politics because of the alignment of the working-class vote with university-educated middle-class voters.
Premises
Counter-arguments
This wasn’t the result of Brexit; it was the result of Corbyn’s leadership. Labour was not a hard Remain Party like the Liberal Democrats. They campaigned for a second referendum, not to rescind Article 50. Working-class voters did not turn away from Corbyn because of Brexit, they turned against him because they were unconvinced by his radical left manifesto that touted the evils of capitalism. In one poll, voters said the second-biggest concern with Jeremy Corbyn as Prime Minister was that he would spend too much and put the country into more debt. This has nothing to do with Brexit or immigration, just Jeremy Corbyn’s reckless fiscal policy.
Rejecting the premises
[Rejecting P1] The coalition described was already coming apart before the referendum, as the loss of Scotland in 2015 and the long decline in the party's vote across former industrial areas show — so Brexit accelerated and revealed a realignment rather than creating it. [Rejecting P2] The premise also mischaracterises what divided the two groups, since immigration is not straightforwardly an economic interest, and it does not explain why the same voters had supported the party at the previous election under the same leader — leaving the leadership, the manifesto and the party's unresolved second-referendum position, which the other positions in this debate propose, unexcluded.