Why did Labour do so badly in the Brecon and Radnorshire by-election, and what does it mean for the party?

Politics Explained: Jeremy Corbyn’s party saw its vote share plummet in the Welsh seat, and it could be a sign of things to come

There was no doubt that the Brecon and Radnorshire by-election on Thursday was a major boost for the Liberal Democrats. The party overturned a majority of more than 8,000 to win the seat from Tory MP Chris Davies.

Some commentators even suggested the result was a good one for Boris Johnson. Despite losing the seat, the Conservatives performed better than some in the party had feared, amid reports of a poll boost for the Tories under their new leadder.

No one tried to make such a claim about Labour. Jeremy Corbyn’s party picked up just 1,680 votes – 5.3 per cent of the total, half the number the Brexit Party received, and 12.5 per cent less of the vote share than Labour got two years ago. Its candidate, Tom Davies, came within a whisker of losing his deposit.

Supporters of Mr Corbyn are likely to point out that the seat has always swung between the Conservatives and the Liberal Democrats. Labour has not held it since the 1970s, and there was no expectation that it would win it this time around, given that the party came a distant third in the constituency in 2017.

Labour will also have suffered from tactical voting. Many of the party’s supporters are likely to have instead backed Jane Dodds, the Liberal Democrat candidate, given it was abundantly clear that the by-election was a two-horse race between her party and the Conservatives.

Tactical voting was particularly significant in this election because of the presence of a “Remain alliance”, with Plaid Cymru, the Green Party and Change UK standing aside in order to give the party the best chance of winning.

Still, Labour will be concerned that the party’s poor showing in Brecon and Radnorshire appears to be part of a wider trend.

Remain backers are increasingly moving behind the Liberal Democrats and Brexiteers opting for the Conservative or the Brexit Party.

Wales has typically been a Labour stronghold, but polling in the nation suggests it has been overtaken by Plaid Cymru and risks being pushed into third place in the Liberal Democrats. The pro-EU parties are on the rise.

This will worry Labour strategists. If, as seems highly likely, the next election is fought largely on the issue of Brexit, the party risks ending up flailing in the middle, caught between Boris Johnson’s pro-Brexit party and the actual Brexit Party on the one side and pro-EU parties such as the Liberal Democrats and Plaid Cymru on the other.

The tightrope that Labour has been walking between its pro-EU members and Leave voters in its heartlands could end up tying it in knots.

The real test of how big an impact Labour’s reluctance to fully oppose Brexit and back calls a second referendum is having on support for the Liberal Democrats will be the Sheffield Hallam by-election later this year. The contest will elect an MP to replace former Labour MP Jared O’Mara, who announced last week that he would step down in the autumn. The seat is a clear Labour-Lib Dem marginal.

Jeremy Corbyn’s team are not in the habit of obsessively analysing opinion polls, but there is no doubt that the party’s recent loss of support is a concern to them.

It explains why they have shifted closer and closer towards an anti-Brexit position as the Lib Dem resurgence threatens Labour’s dominance of the left.

However, they have done so slowly and falteringly, and there remains a widespread perception that Mr Corbyn and his closest advisers have only shifted grudgingly and half-heartedly, after heavy and sustained pressure from party members and MPs. If they want to convince pro-EU voters that Labour is a genuinely anti-Brexit, they have much work still to do.

Mr Corbyn’s inner circle will not be worried about failing to win a seat Labour has never held. But the party’s fall in the vote share and reports of a similar trend across the country cannot be ignored. With the Conservatives opening up a poll lead under Boris Johnson, and the resurgent Liberal Democrats enjoying a new lease of life, the Brecon and Radnorshire result could be a sign of things to come.