by John Curtice, Stephen Fisher and Patrick English

One of the most dramatic developments during the campaign for the December 2019 general election, whose second anniversary is this weekend, was the decision announced by Nigel Farage on 11 November that the Brexit Party would not contest those seats being defended by the Conservatives. Instead it would concentrate its firepower on those seats currently in the hands of one of the opposition parties. This represented a substantial retreat for a party that just the previous May had topped the poll in the European elections.

But was the decision as important as it was dramatic? Part of the answer to that question depends, of course, on the impact the decision had on the overall popularity of the party where it was continuing to fight. It almost certainly helped to reduce it. In the week leading up to Mr Farage’s announcement, the Brexit Party stood on average in the polls at 16% among those who had voted Leave in the 2016 EU referendum. (It had no measurable support at all among Remain supporters.) A week later, its support among Leave voters had fallen by five points to 11% (while support for the Conservatives was up by five points). By polling day, the party was down to just 4%.

Of course, much of this drop would have been occasioned by the gradual realisation among voters in the relevant seats that the Brexit Party was not standing locally, though the scale of the drop by polling day is too big to be explained by that alone. Equally, some voters will have switched away from the party for reasons that had nothing to do with Mr Farage’s decision. But it certainly looks highly likely that the Brexit Party’s partial withdrawal helped to undermine its level of support where it continued to stand.

Even so, the party still managed to win an average of 5.7% of the vote in those seats in England & Wales that it did fight – potentially enough to have some impact on the relative fortunes of the other parties. But what impact did it have? Mr Farage’s decision appeared to reflect his oft made claim that his party was able to gain the support of voters in Labour-inclined, more working class constituencies that the Conservatives could never reach. Thus, while standing down in Conservative-held seats might help avoid a split in the Leave vote that could help the opposition parties to gain Conservative-held seats, continuing to contest opposition-held seats might help the pro-Brexit Conservatives to gain Labour-held seats and thus the overall majority that Boris Johnson was seeking.

The success or otherwise of this strategy is addressed in our analysis of the constituency election results in the recently published ‘Nuffield’ study of the last election, The British General Election of 2019. It proved far from an easy question to answer.

We could, of course, look at the choices that those who voted for the Brexit Party in 2019 had made at the previous election two years earlier. In fact, according to the 30,000 sample British Election Study internet panel (BESIP), rather more Brexit Party voters had voted Conservative (40%) than Labour (30%) in 2017, suggesting that there was little truth to Mr Farage’s assertion that this party was particularly effective at winning over Labour voters in Labour constituencies. However, what matters here is not how Brexit Party voters voted in 2017, but how they would have voted in the absence of a Brexit Party candidate in 2019.

One way of trying to address this counterfactual question is to compare the performance of the parties where the Brexit Party did and did not stand. At +5.3%, the swing from Labour to Conservative since 2017 was rather higher in seats (In England & Wales) that the Brexit Party contested than it was is those seats that it did not (+4.7%). That suggests that the presence of a Brexit Party candidate did do Labour somewhat more harm than the Conservatives, an observation apparently reinforced by the fact that the swing to the Conservatives tended to be higher the bigger the Brexit Party’ share of the vote.

But if the Brexit Party were winning over Labour voters who would never back the Conservatives, we would anticipate that Labour would have lost support more heavily among Leave voters in seats where the Brexit Party stood than it did in those that it did not. Yet the BESIP data suggest that, if anything, the opposite is true. In seats where the Brexit Party stood, 57% of those who voted Leave in 2016 and Labour in 2017 voted for the party again, compared with just 48% in seats the Brexit Party did not contest. Meanwhile, whereas in those seats the Brexit Party did not contest 39% of Labour Leave voters switched to the Conservatives, in seats where there was a Brexit Party presence only 26% did so. Much of the difference between these two figures is accounted for by the 10% who backed the Brexit Party in seats the party was contesting – suggesting that all the Brexit Party managed to achieve where it stood was to divert the support of Labour Leave voters away from the Conservatives.

This in turn, however, is also probably too bold a conclusion. When the BESIP asked respondents to give both the parties and the leaders a mark out of ten, those Leave voters who switched from Labour to the Brexit Party gave both the Conservatives (3.8) and Boris Johnson (5.3) a lower score than those who switched from Labour to the Conservatives (6.2 and 7.1 respectively), suggesting that perhaps not all of those who switched from Labour to the Brexit Party would have swung behind the Conservatives in the absence of a Brexit Party candidate.

In the absence of data on the second preferences of those who voted for the Brexit Party, we modelled the behaviour of Labour Leave voters in seats that the Brexit Party did not contest (taking into account demographics and evaluations of the parties and leaders) and then applied the resulting equation to those voters who elsewhere switched from Labour to the Brexit Party. This suggested that in the absence of a Brexit Party candidate, 70% of those who switched from Labour to the Brexit Party would have instead backed the Conservatives, while just 30% would have stuck with Labour.

It is on this basis that we conclude that the Brexit Party’s decision to continue to fight opposition held seats cost the Conservatives seats they might otherwise have won. If we apply that 70:30 ratio to the share of the Brexit Party’ share of the vote in each constituency, we find that there are around 25 seats that Labour managed to retain that might otherwise have fallen from its grasp – many of them in the North of England and the Midlands – and enough to give the Conservatives an overall majority of 130.

Meanwhile, because there was a national swing from Labour to the Conservatives anyway, the Brexit Party’s decision to stand down in Conservative-held seats helped save the Conservatives from defeat in at most a small handful of Remain-inclined seats.

The squeeze on Brexit Party support during the 2019 election campaign, a squeeze that was probably accelerated by its decision to vacate the contest in Conservative-held seats, played a role in enabling the Conservatives to unite much of the Leave vote behind it, an outcome that was central to their success in winning an overall majority of 80. Even so, the Brexit Party’s continued presence in seats that the opposition parties were defending still acted as something of a brake on that achievement. Small though its tally of votes might have been, under the first-past-the-post electoral system, it was still enough to make a significant dent in the size of the Conservative majority and in reducing the extent of the breach in Labour’s so-called ‘Red Wall’. Little wonder that, in the wake of the outcome of the Old Bexley & Sidcup by-election, commentators are now wondering what role, if any, the Brexit Party’s successor, Reform UK, might play at the next general election.

This blog is also to be found on the What UK Thinks website.

            The British General Election of 2019, by Robert Ford, Tim Bale, Will Jennings and Paula Surridge is published by Palgrave Macmillan.