LONDON — There was a relief for the UK's main opposition Labour Party early on Friday morning when it unexpectedly won a parliamentary by-election at Batley and Spen in the north of England.

It held off a challenge from the ruling Conservatives to hold the West Yorkshire seat by a mere 323 votes. Labour has held the seat since 1997 and victory was crucial for party leader Sir Keir Starmer, under pressure following recent election defeats.

The winner, Kim Leadbeater, is the sister of Jo Cox, the seat's former MP who was murdered by a far-right extremist a week before the Brexit referendum in June 2016.

Leadbeater won 13,296 votes for Labour, narrowly ahead of the Conservatives' 12,973, a disappointment for their challenger Ryan Stephenson. The main opposition party was also threatened by veteran left-winger George Galloway, whose campaign targeted Muslim voters, but his 8,264 votes were not enough to prevent a Labour win.

"I'm absolutely delighted that the people of Batley and Spen have rejected division and they've voted for hope," the winning candidate said.

"Fantastic result for the brilliant and brave Kim Leadbeater," Starmer tweeted soon after the result was announced. "Kim ran a positive campaign of hope, in the face of division."

The campaign was one of the most bitter and dirty in recent British political history. Labour activists claimed they were abused and assaulted while out campaigning.

The party has been struggling to reinvent itself since Starmer took over the leadership from Jeremy Corbyn in the wake of the December 2019 general election debacle, which saw Boris Johnson's Tories win an 80-seat majority.

Whereas the prime minister has molded the Conservatives firmly behind his pro-Brexit stance, Labour's divisions over the issue have proved hard to put to rest.

The Tories recently took England's northeastern seat of Hartlepool from Labour, who had held the traditionally working-class constituency since 1974. The ruling party has also been boosted by the UK's successful coronavirus vaccine rollout.

However, the Conservatives have suffered recently from various political scandals — one of which notably led to Matt Hancock's resignation as health minister — and this may have contributed to the Batley and Spen result.

Jo Cox's murder exposed the UK's profound divisions on the issues of Europe and immigration in particular. A fervent supporter of British membership of the EU and a defender of the rights of refugees, Cox was a strong advocate of diversity.

Her killer was found guilty of murder in November 2016 and given a life sentence. — Euronews