Sir Keir Starmer on Friday opened a path to No10 through Scotland with a “seismic” by-election win in Rutherglen and Hamilton West.
Labour crushed the Scottish National Party, with a swing of more than 20 per cent.
The party’s candidate Michael Shanks secured 58 per cent of the votes, more than twice that of his SNP rival Katy Loudon.
Significantly the Tories’ vote collapsed, winning only 3.9 per cent and embarrasingly losing their deposit.
If the swing to Labour was replicated at a General Election it could mean Labour gaining 40 seats in Scotland, compared to the one it currently holds.
Rutherglen was the first recall by-election in Scotland so the result needs to be treated with considerable caution.
It was held after Margaret Ferrier, who had won the seat in 2019 with a majority of 5,230, had the SNP whip removed after breaching Covid rules in 2020.
It also comes amid a police investigation into the SNP.
But it still opens up the prospect of Labour winning dozens of seats in Scotland, which makes it far more likely that Sir Keir could win the next General Election, expected next autumn, with an overall Commons majority.
Responding to the result, the Labour leader said: “This is a seismic result. People in Rutherglen and Hamilton West have sent a clear message – it is time for change. Voters want to move on from two SNP and Tory governments that offer only more division, more chaos and more infighting.”
Speaking to journalists from Labour’s HQ in Rutherglen later on Friday, he said: “It was a big step in the right direction” on his road to Downing Street.
“This was a must-win for us, and the size of the win, I think, vindicates the positive campaign that we ran.“But we accept this humbly, this is a step on the journey.
“We’ve made the case for change here in Rutherglen, we need to make the case for change across the whole of Scotland, and earn all of the votes.
“But, as I have said many, many times, the route to a Labour election win at the next general election runs through Scotland, because if I’m privileged to serve I want to be the prime minister for the whole of the United Kingdom, not just of the United Kingdom.”
Sir John Curtice, Professor of Politics at Strathclyde University, stressed the result was similar to that in 2010 before Scottish independence came to dominate politics north of the border so heavily and that it now “looks possible” that Labour could win 24 seats in Scotland at the next election, an often quoted target.
Emphasising that the result was similar to the “very seismic” swing to Labour in the Selby and Ainsty by-election in July in North Yorkshire, he told BBC Radio 4’s Today programme: “By election swings on this scale are the kinds of swings that historically at least oppositions have secured when they are going to go on to win the next General Election.
“If Keir Starmer can start winning seats in Scotland, his chances of getting an overall majority and avoiding a hung Parliament increase quite significantly.”
Shadow Foreign Secretary David Lammy, who campaigned in Rutherglen, told The Standard before the result came in and as MPs digested its wider implications: "Most people thought it would take at least two terms to come back, is the truth.
“Keir’s done a spectacular job. He’s had to do the job of Neil Kinnock and Tony Blair, in just under four years. It’s remarkable, actually, what he’s achieved."
Mr Shanks won 17,845 votes, well ahead of the 8,399 votes returned for Ms Loudon, and now has a majority of 9,446.
The Scottish Conservatives came in third place, with Thomas Kerr polling 1,192 ahead of Scottish Liberal Democrat candidate Gloria Adebo and Scottish Green Party candidate Cameron Eadie who secured 895 and 601 votes respectively.
A total of 30,531 votes were cast in the by-election, with turnout standing at 37.2 per cent, well below the 66.5 per cent turnout in the last general election.
SNP leader and Scottish First Minister Humza Yousaf, who made frequent visits to the constituency during the election campaign, stressed his party was facing “some very difficult circumstances”.
But he said the buck would stop from him if his party failed to hold on to the seat, and afterwards he conceded it had been a “disappointing night” for the SNP.
He posted on X that “circumstances of this by-election were always very difficult for us” with Mr Yousaf adding the “collapse in the Tory vote” had gone straight to Labour, saying this was a “significant factor” in the result.
But the SNP leader added: “We lost this seat in 2017, and like 2019 we can win this seat back.
“We will reflect on what we have to do to regain the trust of the people of Rutherglen & Hamilton West.”
Mr Shanks said afterwards it was the “honour of his life” to be elected as MP for the area.
Speaking at the count in Hamilton he said: “The message from tonight is a resoundingly clear one - we have had more than enough of managed decline, more than enough of division, more than enough of distracted, chaotic government.”
Mr Shanks added the result showed that “there is no part of this country where Labour can’t win”.
Scottish Labour leader Anas Sarwar meanwhile said: “I think Scottish politics has fundamentally changed tonight. The people of Rutherglen and Hamilton West have demonstrated that Scotland are sick of two failing governments. They want the incompetence, chaos and the division to come to an end.”
Stephen Flynn, the SNP’s leader in Westminster, said it was too soon to determine all the factors that contributed to "obviously a tough night" for his party.
"But what we do know is that we’ve lost by a significant margin, we know that our vote has not turned out," he told BBC Breakfast.
"And we know that we need to remotivate people to vote for the Scottish National Party. That’s as a big challenge," Mr Flynn added.
