The Liberal Democrats swept to victory in the Devon seat as Richard Foord overcame a Tory majority of just over 24,000 votes – the largest ever overturned at a by-election.
Lib Dem leader Sir Ed Davey said it was the “biggest by-election victory our country has ever seen”, adding that the result should be a “wake-up call” to Tory MPs about Mr Johnson’s leadership.
Labour’s Simon Robert Lightwood took Wakefield after winning the west Yorkshire seat by almost 5,000 votes, overturning a smaller Conservative lead of just over 3,000 votes.
Labour leader Sir Keir Starmer said the result shows that the country has “lost confidence in the Tories” and showed his party was “ready for government”.
Tory chair Oliver Dowden resigned after the party’s crushing double loss – saying he shared the feelings of Tory supporters who were “distressed and disappointed by recent events” in a letter to the PM.
The double defeat will raise further questions for PM, currently in Rwanda for the Commonwealth summit, who insisted on Thursday that it would be “crazy” to step down even if he lost both by-elections.
Mr Foord won in Tivertonby over 6,000 votes as he became the first non-Tory MP in the seat since it was created back in 1997. The 30,000 swing represents the largest majority, in raw votes not percentage swing, ever overturned at a by-election.
Mr Foord used his victory speech to call on Mr Johnson to “go and go now”, saying the result showed that voters think “enough is enough”.
The former Army major added: “Ours is a great country and there’s no greater part of it than Devon. But everyday Boris Johnson clings to office, he brings further shame, chaos and neglect.”
The result in Wakefield was also a significant win for Starmer and Labour, who have not gained a seat in a by-election since Corby in 2012.
In his victory speech in Wakefield, Mr Lightwood said the result showed Labour was “rebuilding the red wall”, adding: “The next Labour government has been born in this room tonight.”
Former No 10 adviser Tim Montgomerie, creator of ConservativeHome website, said the “massive” result in Tiverton showed why Mr Johnson had to go. “This is a crisis for the Conservative party,” he told Sky News.
He added: “Voters are reacting to the character of the prime minister. They are rejecting the character of the prime minister. And if the Conservatives don’t act soon … the whole Conservative party will be judged. We cannot let this situation continue.”
Gavin Barwell, former No 10 chief of staff under Theresa May, said the results should show the Conservatives it is “time to wake up before it is too late”.
“Finally someone in the cabinet says ‘Enough is enough’,” he tweeted on Mr Dowden’s exit. “These by-elections – particularly Tiverton – show the Conservative Party is sleepwalking to defeat at the next election.”
James Johnson, former pollster at No 10, said there was “only one person to blame for the Wakefield result” – pointing to Mr Johnson and Partygate as the main reason swing voters cited for opting for Labour.
Naomi Smith, chief executive of the Best for Britain, campaigning for anti-Conservative electoral pact, said the majorities at both by-elections “could not have been overturned without tactical voting and an unofficial electoral pact”.
Urging Starmer and Davey to collaborate, she added: “Labour and the Lib Dems mustn’t rest on their laurels, repeating this success will be much more difficult in a general election. Our polling proves they will need to collaborate to defeat the government.”
Labour ‘rebuilding red wall’, says Wakefield by-election winner
Throughout the night, Lib Dems in Tiverton were confident that they had secured a big swing from the Tories. Treasury spokesperson Christine Jardine MP told The Independent that the Tories were “haemorrhaging votes”.
However, the sheer scale of the historic victory only became clear early on Friday morning when Labour sources started to hint that their vote in Devon had collapsed – suggesting many people had voted tactically.
As vote counting got under way, Lib Dem leader Ed Davey sent out an optimistic tweet hinting at the victory in the so-called blue wall seat in the south of England. “Looks like I’m going to need a bigger hammer,” he wrote.
Then at 2:52am the Lib Dems called the election in their favour. In a bullish statement, a spokesperson said that they were looking at a “clear win” which would deliver a “devastating blow” to Tory MPs”.
The Lib Dem win adds to a streak of successes, including a win against the Tories in Chesham and Amersham last June and North Shropshire in December.
Both seats came up for re-election after their respective Tory MPs resigned in disgrace. In Wakefield, Imran Ahmad Khan stepped down after being convicted of sexually assaulting a teenage boy.
In Tiverton, Neil Parish resigned after admitting to watching porn in the House of Commons.
The turnout for the by-election in Tiverton and Honiton was 52.3 percent, the local authority said – significantly higher than Wakefield where the turnout was 39.09 percent.