KEIR Starmer is the leader with most to fear from defeat in Rutherglen & Hamilton West because of its implications for the general elections, a leading pollster has said.

Mark Diffley said the UK Labour leader would be more nervous than either the SNP’s Humza Yousaf or Scottish Labour’s Anas Sarwar about the outcome of the byelection. 

With Labour widely expected to win the contest, the founder of the Diffley Partnership said failure would be a “big loss” and “diminish their hopes” for next year.

Fourth on Labour’s target list in Scotland, the seat is one of the most marginal in the country, with Labour needing just a 5% swing to gain it from the SNP.

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The byelection was confirmed on Tuesday after voters threw out former SNP MP Margaret Ferrier in a recall petition triggered by her breaking Covid lockdown rules.

Ms Ferrier won the seat in 2019 by 5,230 votes, but had the party whip removed in 2020 after taking a train from London to Glasgow while knowing she had the virus.

She was sentenced to 270 hours of community service after admitting reckless conduct and suspended from the Commons for 30 days, leading to the recall petition.

Mr Diffley was speaking in an online discussion about the byelection with Kezia Dugdale, the former Scottish Labour leader who now leads the John Smith Centre at Glasgow University, in an event organised by lobbyists Charlotte Street Partners.

He said: “I would argue it’s probably, marginally, a bigger challenge for Labour than it is for the SNP. We're kind of primed now to think that Labour are going to win.

“A lot of this is about expectations, the expectation now is that Labour will win.

“So I think if Labour don’t it will feel like – it will be – quite a big loss.”

He said Labour “probably will win” but the size of its majority would be significant.

Labour won the seat from the SNP in 2017 by just 265 votes, or 0.5%, before losing it back to the SNP two years later . 

“If Labour can’t win this seat then it really does diminish their hopes next year,” Mr Diffley said. "I think both Anas and Humza have got both a lot to gain and a lot to lose.”

He said Sir Keir would be the "most nervous" leader involved in the byelection.

He said the 8,000 people who voted Tory in the seat in 2019 could play a big part if they voted tactically for one side. 

Ms Dugdale said she was unsure if Labour would try to attack the SNP or use the byelection to attack the Tories as part of the UK-wide effort by Labour to return to power.

She said: “It’s not clear to me yet which of these two enemies they’re going to pick.

“But I do think they need to pick one and stick with it.”

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She said the SNP’s strategy would be to talk about Scottish independence to appeal to its own voters while attacking Sir Keir’s stance on issues like the two-child benefit cap.

Mr Diffley said Mr Yousaf could use the byelection to “get on the front foot and test his mettle” after a difficult start to his leadership of the SNP.

Many in the SNP have already written off their chances in the byelection, and plan to put a loss down to exceptional circumstances and an atypical MP.