Sir Keir Starmer has said voters have let out a “cry for change” after the Conservatives were dealt two by-election defeats in what were considered safe seats.
Rishi Sunak insisted on Friday that the next general election is not a “done deal” after the Tories managed to narrowly cling on to Boris Johnson’s old Uxbridge and South Ruislip seat.
Labour won in Selby and Ainsty and the Liberal Democrats in Somerton and Frome, both overturning majorities of about 20,000 in what polling experts said spelled “deep electoral trouble” for the Tories.
But the Prime Minister was not changing his approach, vowing to “double down” on his existing policies to win over the public as he seized on a slender victory in west London.
Sir Keir placed some blame for the failure to capture that seat on his own party’s mayor in the capital, Sadiq Khan, over his expansion of the Ulez charge on high-pollution vehicles.
The Labour leader said the London mayor should “reflect” on the policy after new Tory MP Steve Tuckwell painted the vote as a referendum on the toll.
The councillor won by 495 votes – massively down on the 7,210 majority the former prime minister had won.
In Selby and Ainsty, 25-year-old Keir Mather will become the youngest MP in the Commons after overturning a 20,137 majority to win by 4,161 votes.
The swing from Conservatives to Labour of 23.7 percentage points is the second largest swing managed by Labour at a by-election since 1945.
Sir Keir went to the North Yorkshire constituency – not far from Mr Sunak’s seat – to celebrate the “historic” victory at Selby Town Football Club.
He told supporters it was the “biggest majority we’ve ever turned over in the history of the Labour Party”.
“You voted for change. You put your trust in the Labour Party, and we hear you,” he said.
“We hear that cry for change away from the chaos, away from those rising bills, the crumbling public services – a cry for change and we will deliver.”
Mr Sunak welcomed the one piece of good news after a bad night by visiting the Rumbling Tum Cafe in Ruislip with Mr Tuckwell.
The Prime Minister told broadcasters: “By-elections, mid-terms for an incumbent Government are always difficult. They rarely win them.
“The message I take away is that we’ve got to double down, stick to our plan and deliver for people. That’s what I heard when I was out on the doorsteps and that’s what we’re going to do.
“We’re going to work incredibly hard to deliver on our five priorities and earn people’s trust for the next election.”
He argued holding on to the seat showed there was hope for the Tories at the general election expected next year.
Mr Sunak said: “Westminster’s been acting like the next election is a done deal. The Labour Party has been acting like it’s a done deal, the people of Uxbridge just told all of them that it’s not.”
For the Lib Dems, a 29.0 percentage point swing in Somerton and Frome saw a 19,213 Tory majority turned into an 11,008-vote cushion for new MP Sarah Dyke.
In a victory visit to Frome, Lib Dem leader Sir Ed Davey said the result showed his party was once again winning votes in its former West Country heartland.
“It’s time to end this shameful spectacle. It’s time for a general election to end this Conservative circus,” he told supporters.
The victory means Sir Ed has become the first party leader since Paddy Ashdown in the 1990s to win four by-elections.
Despite Labour’s success in North Yorkshire, the failure to secure victory in Uxbridge and South Ruislip in west London has led to a blame game among senior figures over Mr Khan’s plan to expand the ultra-low emission zone (Ulez) to cover outer boroughs.
Sir Keir said: “Uxbridge was always going to be tough. We didn’t take Uxbridge in 1997 and we knew Ulez was going to be an issue.
“And of course we all need to reflect on that, including the mayor needs to reflect on that.”
Mr Khan said he was “disappointed” Labour did not win, but welcomed the swing towards Labour and said his Ulez decision was a “tough one, but the right one”.
Labour candidate Danny Beales had distanced himself from the policy, saying it was “not the right time” to expand the £12.50 daily charge for cars which fail to meet emissions standards.
The defeat in the seat was dubbed “Uloss” by a party insider in a sign of the unease at Mr Khan’s plan.
In his victory speech, Mr Tuckwell said Mr Khan had cost Labour the seat, saying: “It was his damaging and costly Ulez policy that lost them this election.”
Deputy Labour leader Angela Rayner and shadow justice secretary Steve Reed acknowledged it had been a factor in the campaign and called for Mr Khan to change course.
Mr Reed told the PA news agency: “I think those responsible for that policy will need to reflect on what the voters have said and whether there’s an opportunity to change.”
Polling expert Professor Sir John Curtice said the by-elections suggest the Tories are in “deep electoral trouble”, with the results showing the Conservatives are 21 percentage points behind, similar to the national polling.
He noted the similarity to the run up to the 1997 Labour landslide, telling BBC Radio 4’s Today programme “history is not bound to repeat itself” but the precedent indicates the difficulty the Tories are in unless they can turn things around.
But he said Labour must ask why its hold on the electorate is “apparently so weak” that when a local issue like Ulez comes up they “don’t perform as they should”.
For Mr Sunak, the defeats happened as MPs drifted away from Westminster to begin their summer break, complicating any plotting against him by any concerned colleagues.
There had been speculation that Mr Sunak may try to promptly reset his administration with a Cabinet reshuffle on Friday, but Downing Street sources made clear this was not going ahead.
