Labour has comfortably won the Chester by-election – the first public vote since Boris Johnson and Liz Truss were ousted from Number 10.
Samantha Dixon retained the seat for her party with 17,309 votes – a 61% share and nearly 11,000 more than the Conservative candidate.
Labour was expected to win, but the margin was bigger than in 2019 when the gap was 6,164 votes.
It represents a 13.8% swing from Tory to Labour, the sixth largest between the parties since 1945, and more than the 12.7% in Wakefield in June.
It is also the worst result for the Conservatives in Chester since 1832, with candidate Liz Wardlaw getting 6,335 votes, or 22.4%.
Politics latest: Labour retains Chester with increased 11,000 margin
Ms Dixon told Sky News the result was a “resounding mandate” for Labour, and in her victory speech said the Tories were “on borrowed time and people want to change”.
She added: “People in Chester and across our country are really worried.
“Worried about losing their homes because they can’t afford the mortgage repayments or the rent, worried about whether they can put the heating on, worried about whether they can put food on the table for their families.
“This is the cost of 12 years of Conservative Government. The Government, which has wreaked havoc with our economy, destroyed our public services and betrayed the people who put their trust in them at the last general election.”
Sky’s chief political correspondent, Jon Craig, described it as a “crushing defeat” for the Tories and “ominous” for the party’s chances at the next election.
However, he said it would be harsh to personally blame new prime minister Rishi Sunak for the result.
Analysis – Not just a bad result, but a disaster
It comes after a big disappointment for the Conservatives in two summer by-elections which saw Labour snatch Wakefield and the Lib Dems secure a historic victory in Tiverton and Honiton.
The Chester contest was triggered by the resignation of Labour MP Chris Matheson, who was suspended in October after two allegations of sexual misconduct from a former staff member were upheld.
The result follows a slump in opinion polls for the Conservatives after a raft of reshuffles in their top ranks.
The party saw a small bounce in their numbers after Rishi Sunak entered Downing Street last month – the third Tory leader this year – but the Tories are still regularly polling behind Sir Keir Starmer’s Labour Party.
This is the first of two by-elections this month, with another taking place on 15 December in Stretford and Urmston, Greater Manchester.
That vote was called after Labour’s former shadow education secretary, Kate Green, announced she was standing down to become deputy mayor of Manchester.