The British Labour party has regained a Glasgow seat in the Rutherglen and Hamilton West by-election as the SNP vote plummeted.
Labour leader Keir Starmer, reacting to the victory in the early hours of this morning, described the result as "seismic" and said that it was time for change.
The swing from SNP to Labour was 20%, which is twice what was being predicted.
The Labour candidate Michael Shanks got nearly 18,000 votes, roughly twice the number of the SNP candidate Kate Loudon.
The poll was taken after the ousting of the sitting MP Margaret Ferrier, who was expelled from the SNP after breaching Covid rules.
She was forced out by a petition of local voters after she refused to resign.
It was also the first test of the new SNP leader Humza Yousaf.
Her husband Perter Murrell, who was the SNP chief executive, and the party's treasurer were also taken in for questioning.
Mr Starmer needs to win back Labour seats in Scotland to win government in Westminster.
Up until 2015, Labour could count on getting at least 40 seats. For context, the current Conservative majority is 60.
However, its vote collapsed, leaving just one Labour MP.
A feature of recent Scottish elections has been tactical voting, with people going for whoever is most likely to beat the SNP, who have been in charge of the Scottish parliament for 16 years.
In this poll the Conservative vote dropped by 11%, showing that in this case Labour were the party most likely to benefit from that scenario.
Labour 'won back trust' - Starmer
Mr Starmer said: "I have always said that winning back the trust of people in Scotland is essential.
"Tonight's victory is the culmination of three-and-a-half years of hard work and humility on that journey.
"I am grateful to everyone who has put their faith in us today - we will work every day to repay it.
"Voters across Scotland and across Britain want a government determined to deliver for working people, with a proper plan to rebuild our country.
"They want to move on from two SNP and Tory governments that offer only more division, more chaos and more infighting."
Mr 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".
He declared: "Labour can kick the Tories out of Downing Street next year and deliver the change people want and this country so badly needs. Tonight is one part of that journey."
Scottish Labour leader Anas Sarwar meanwhile said: "This is an absolutely extraordinary result; a seismic result and I think this will send shockwaves through the SNP and a historic moment in Scottish politics.
"I think Scottish politics has fundamentally changed tonight. The people of Rutherglen and Hamilton West have demonstrated that Scotland is sick of two failing governments. They want incompetence, chaos and the division to come to an end."
He rejected the idea that the win was fueled by turmoil within the SNP, adding the result was "humiliating" for Mr Yousaf's party.
However, he said the significant swing to his party was "even beyond our expectations".
