This wasn’t just a bad result for the Conservatives and Rishi Sunak, it was a disaster.

The Tory share of the vote in the City of Chester by-election slumped to only 22.4%.

Tory MPs in red wall seats in the north of England will be even more despondent about their prospects at the next general election after this crushing defeat.

The swing of 13.8% from the Conservatives to Labour was the sixth worst by-election performance for the Tories in a fight with Labour since 1945.

It was also the worst result for the Conservatives in Chester since 1832. Spare a thought for Liz Wardlaw, the poor hapless Tory candidate, who watched Labour’s majority leap from just over 6,000 to nearly 11,000.

A terrible start, therefore, for Mr Sunak in his first by-election as prime minister, though to be fair it would be harsh to blame him personally for this disaster.

For Labour, however, Christmas has come early – its 61.2% vote share was well above the 49.6% won by the now disgraced Christian Matheson at the 2019 general election.

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Let’s not forget why this by-election was being fought: Mr Matheson was found guilty of serious sexual misconduct towards a junior member of his staff and was facing a four-week suspension from the Commons when he resigned.

That should have been a gift to the Tories. But it seems to have had little impact. The new MP, Samantha Dixon, campaigned on the cost of living crisis, improving bus services and tackling the dumping of sewage in the River Dee that flows through the city.

The swing to Labour was short of the 17% suggested by national opinion polls. But the party only needs a swing of 12% for a general election victory.

With another by-election due in two weeks, in the safe Labour seat of Stretford and Urmston, and another in the new year in West Lancashire after the resignation this week of the Labour MP Rosie Cooper, Labour will be looking at driving up its vote share and driving the Tories’ down.

Governing parties always dismiss by-election defeats as a mid-term protest vote. But the collapse in the Tory vote here in Chester is ominous for the Conservatives at the next election.

Speaking to Sky News after her victory, Ms Dixon claimed the result was a “resounding mandate”. True.

A few moments earlier, in her victory speech, she said the Conservative government was “on borrowed time”. Unless the Tories can stage a spectacular recovery next year, that may be true as well.