The Prime Minister instigated the election in June in order to secure a large overall majority and thereby, she hoped, the ability to deliver her vision of Brexit. In the event, of course, rather than increasing her overall majority, she lost it entirely, leaving her forced to seek a ‘confidence and supply’ arrangement with the DUP. But the fact that Mrs May’s stratagem did not reap its intended dividend still leaves open the question of whether voters’ attitudes towards Brexit did actually affect how they voted in the election, and can be said in any way to have accounted for the Prime Minister’s disappointment.

In a new analysis paper published today, we bring together some of the key survey evidence on that question available to date. The paper shows, using a variety of sources, that attitudes towards Brexit did help shape some of the movements in support as compared with 2015. The Conservatives gained ground amongst Leave voters but lost votes amongst those who had backed Remain. Meanwhile, although Labour support did increase amongst Leave voters, the rise was stronger amongst their Remain counterparts. As a result, the gap between the two parties’ supporters in their attitudes towards Brexit, already evident in the EU referendum, widened yet further.

In some respects, this pattern was rather surprising. The two parties with the clearest stances on Brexit are the Liberal Democrats and UKIP. The former want a second referendum before Brexit proceeds, the latter backs the hardest possible Brexit. Yet neither prospered at the election. Instead, voters used the two largest parties, internally divided and sometimes highly ambiguous on the issue as they were, to register their views about Brexit.

As a result, the two parties are now backed by very different electoral coalitions on the Brexit issue. For every Remain voter who voted Conservative there are perhaps as many as two Leave voters who did so. Consequently, the government has an electorate that, for the most part, is expecting it to deliver the promises of the Leave campaign in the referendum on June 23 2016. Labour, in contrast, has roughly two Remain voters for every one that voted Leave. Most of its voters would prefer a ‘soft’ Brexit, if indeed Brexit has to happen at all. There is, then, quite a strong incentive for the two parties to adopt divergent stances on Brexit as the withdrawal negotiations proceed.

The pattern of voting in 2017 has also brought about an important change in the ideological dividing lines between Conservative and Labour supporters. Traditionally, whether someone voted Conservative or Labour has primarily reflected whether they were on the ‘left’ or the right’, that is, whether they want the government to do a little more or a little less to try and reduce inequality.

But the Brexit referendum was about a different ideological divide – between social liberals and social conservatives. (The former are comfortable with living in a diverse society, while the latter prioritise social cohesion.) Social liberals voted heavily to Remain while social conservatives mostly backed Leave. In contrast, those on the left and those on the right hardly differed at all in how they voted in the EU referendum.

So, because the Conservatives gained ground amongst Leave voters but lost support amongst Remain supporters, its vote in 2017 was markedly more socially conservative than in 2015. Meanwhile, because Labour support increased more amongst Remain voters than Leave supporters, its vote became rather more socially liberal.

Not that the traditional left/right divide in Labour/Conservative support has disappeared; indeed, it was probably just as big in 2017 as in 2015 (though despite the allegedly left-wing character of Labour’s appeal to the electorate, it is not clear that the party was particularly successful at gaining ground amongst left-wing voters). However, the left/right divide does now sit alongside a social liberal vs. social conservative divide, which is now almost as important as the left/right split in differentiating the two parties’ sets of supporters.

However, the pattern of voting in 2017 does mean that the demographics of party support are no longer dominated by social class. Rather, it is age that is now by far the biggest demographic division in British politics, a reflection in part, at least, of the fact that younger voters voted Remain and older ones, Leave. Meanwhile, graduates (who predominantly voted Remain) swung to Labour in 2017, while those without any qualifications moved towards the Conservatives. Support for Labour amongst graduates is now almost as high as it is amongst those in working class occupations.

These unfamiliar demographic patterns raise awkward questions for both Labour and the Conservatives. Labour still thinks of itself as the party of the working class, but in practice it is now almost as accurate to regard it as the party of university educated social liberals. This gives rise to debate in the party about whether it should be trying to recapture the ‘left behind’ working class voters that it appears to have lost – whose views on Brexit are very different from those of the party’s university educated voters. Meanwhile the Conservative party finds itself backed by a predominantly Leave electorate whose views on how the British economy should be run are sharply at odds with those of the party’s traditional allies in big business.

Brexit has, for the time being at least, reshaped the contours of Conservative and Labour support – and in so doing leaves both parties facing unfamiliar strategic dilemmas with which they may well struggle to come to terms.