The Conservatives have suffered a record loss after Selby and Ainsty voted against the government at a by-election.
A vote in the North Yorkshire seat was triggered last month after Boris Johnson ally Nigel Adams resigned from the House of Commons when he failed to get added to the House of Lords.
Labour has overturned a Conservative majority of 20,137 – the largest majority reversed at a by-election.
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Labour’s Keir Mather – aged just 25 – won 16,456 votes, compared to the 12,295 cast for the Tory’s Claire Holmes. This equals a majority of 4,161.
The Conservatives had attempted to manage their expectations in the run-up to the three by-elections, although they aimed to keep a hold of Selby and Ainsty.
The loss means that for the first time since it was created in 2010, the constituency will not be represented by the Tories – or indeed Nigel Adams.
Rather, Mr Mather will now represent Selby and Ainsty voters in Westminster under Sir Keir Starmer’s leadership.
A swing of at least 17.9% was needed by Labour to win the seat – they need a nationwide change of 12% to form a majority at the next election.
This is a larger change than Sir Tony Blair achieved in 1997 when New Labour came to power.
On the night, the swing ended up being 24.1. A similar swing at a general election would give Labour more seats than they won in 1997.
Labour leader Sir Keir said: “This is a historic result that shows that people are looking at Labour and seeing a changed party that is focused entirely on the priorities of working people with an ambitious, practical plan to deliver.
“Keir Mather will be a fantastic MP who will deliver the fresh start Selby and Ainsty deserves.
“It is clear just how powerful the demand for change is. Voters put their trust in us – many for the first time. After 13 years of Tory chaos, only Labour can give the country its hope, its optimism and its future back.”
In response, veterans’ affairs minister Johnny Mercer told Sky News that he reckons Conservatives stayed at home, rather than voting for Sir Keir Starmer.
He added that he felt the seat could be won back in the next general election.
One of the key factors in the Conservatives’ loss of Selby and Ainsty is its high rate or mortgage-holders.
It is in the top 40 seats in England and Wales for people with loans out on their homes who will have been hammered by rising interest rates – a point Labour would have campaigned on vociferously.
The loss of Selby and Ainsty bodes badly for the party ahead of a general election expected next year; it has a large population of over-60s, a majority of Leave voters, is 94% white British and is fairly affluent.
In other words, it should have been a very safe seat.