Senior Labour figures reacted with happy tears and cheers as news broke that the party is set for a huge landslide general election victory - with Wes Streeting breaking down and Andy Burnham celebrating like a football fan.
Mr Streeting, lined up to be the country's new Health Secretary, 'welled up' as the exit poll was revealed at 1pm - tipping Sir Keir Starmer's party for a majority of 170.
And Greater Manchester mayor Mr Burnham, a former Health Secretary himself, punched their air and appeared lost for words on Sky News before eventually exclaiming: 'It's brilliant.'
But Labour's deputy leader Angela Rayner was more cautious when interviewed on BBC News about the poll figures, saying she was 'not counting her chickens'.
Sir Keir's projected majority would be just short of Sir Tony Blair's 179 in 1997, while Rishi Sunak's Conservatives are expected to win just 131 seats - 234 down from their general election victory under Boris Johnson five years ago.
Greater Manchester's Labour mayor Andy Burnham gave a football fan-style celebration when news of the exit poll figures was announced on Sky News where he was a studio guest
Shadow Health Secretary Wes Streeting is said to have 'welled up' in a BBC studio
The Liberal Democrats are predicted to make 53 gains, reaching 61 MPs, with Reform winning 13 seats and the SNP slumping from
The BBC's chief political correspondent Henry Zefferman said: 'I’ve just watched Wes Streeting, the shadow health secretary, as he saw the exit poll announced in our Westminster studio.
'His eyes welled up with tears as Rachel Burden said the words "Labour landslide".'
Mr Streeting later told BBC News: 'Of course I'm delighted by the exit poll. I've seen many exit polls over the years.
'They don't tend to look like these ones, and if we have won this general election, that is historic for the Labour Party - but even more importantly, is an opportunity for the country, for us to rebuild our economy and our public services and rebuild trust in politics.'
He also expressed some frustration when it was put to him that the figures did not show resounding enthusiasm for the party in seats that voted for it five years ago,
Mr Streeting hit back by saying: 'Keir Starmer could literally be on his way to Buckingham Palace to be made Prime Minister and pundits would be saying, "Oh, it's still a disappointing night for Labour". I mean, come on, give me a break - I've had enough of this now.'
Appearing alongside the Conservatives' Dame Andrea Leadsom on BBC News, Mr Streeting added: 'I'm afraid the reason why the Conservative Party has been swept out is because it's been a clown show and people are paying a heavy price for it.
'The reason the Labour Party has been in the position it's in is because we've changed. And we didn't choose the unity of the graveyard either after 2019 - we had some fights and some arguments to reconnect the Labour Party with the people we lost and the people we need to win over to form a majority.
'The Conservative Party - I mean, I actually don't care about the Conservative Party - their problem not mine.
The exit poll predicting a thumping victory for Labour was revealed at 10pm as voting closed
Labour's deputy leader Angela Rayner said she was 'not counting her chickens' but suggested voters were punishing the Conservatives for their past 14 years in power
Labour leader Sir Keir Starmer, pictured arriving to vote this morning alongside his wife Victoria, is projected by tonight's exit poll to win a landslide 170 majority
'We've got to clear up the mess of the Conservative Party, just like the Downing Street cleaners had to clean the vomit up after Boris Johnson.'
Meanwhile, Mr Burnham hoisted his arms in the air as the figures were announced on Sky News where he was a studio guest alongside former Scottish Conservatives leader Baroness Ruth Davidson.
He also closed his eyes and held his hands together in front of his face in a praying motion, as he gasped in gleeful astonishment at the numbers.
Former Labour cabinet minister Lord Mandelson, one of the key figures behind Sir Tony's 1997 landslide, tonight said he was 'gobsmacked' by the exit poll.
He noted Ms Rayner's caution but told the BBC: 'I'm allowed to be a little bit more gobsmacked. I think that an electoral meteor has now struck planet Earth.
'In a sense it's not surprising given everything the country's gone through over the last 10 years.
'I think it would have required Superman as leader of the Conservative Party to lead them back to some sort of victory and Mr Sunak is not Superman, but I would have to say this: this is an extraordinary achievement for Keir Starmer and his team.
'Nobody in 2019, nobody would have imagined this was possible and they and the team and all the people who've won this campaign deserve absolutely every piece of credit that's coming their way.'
Ms Rayner later told Sky News she believed voters were voters were punishing the Conservatives for the last 14 years.
She described the exit poll as encouraging but stressed the results were not yet in.
Former Labour cabinet minister Lord Mandelson told the BBC tonight he was 'gobsmacked' by the scale of his party's potential victory based on the exit poll numbers
Rishi Sunak, who called the election in the pouring rain outside Downing Street on May 22, is tipped to see his Conservative party slump from 365 to 131 seats
She added: 'Keir has done a tremendous job in transforming the Labour Party and putting forward a programme for government that the country can get behind.
'After 14 years of the chaos and the scandals and the decline we have seen under Tories, I think they are getting punished for that - that's pretty clear in the polls as well.'
Meanwhile, Shadow Foreign Secretary David Lammy suggested a new name for his party's leader - 'Keir Charmer'.
He also insisted he expected to be Foreign Secretary in the new government despite Sky News presenter Kay Burley telling him that Douglas Alexander could 'give you a run for your money' for the job.
Mr Alexander, who held a number of cabinet roles during the Labour governments of Tony Blair and Gordon Brown, has not been an MP since 2015 but is standing this year in Lothian East, Labour's top target in Scotland where the SNP is defending a majority of 2,207.
Mr Lammy said: 'I have seen the tittle tattle in some parts of the right wing media, but I've got to tell you, in preparing potentially for Government, preparing for NATO, preparing for the European Political Community, with war in Europe and huge problems in the Middle East, this is a very serious role.
'Of course I'll serve wherever Keir Starmer wants me to but I do fully expect to be Foreign secretary if we get across the line.'
In the first result of the night, Shadow Education Secretary Bridget Phillipson held Houghton and Sunderland South, with Reform pushing the Conservatives into third place.
Ms Phillipson, who will now expect to be in Sir Keir's first Cabinet, said: 'Tonight the British people have spoken and if the exit poll this evening is again a guide to results across our country - as it so often is - then after 14 years the British people have chosen change.'
Sir Keir gave his first statement after the exit poll was revealed with a post on X, formerly Twitter, in which he said: 'To everyone who has campaigned for Labour in this election, to everyone who voted for us and put their trust in our changed Labour Party - thank you.'
Labour's Shadow Education Secretary Bridget Phillipson held her Houghton and Sunderland South seat in the first confirmed result of the night
Bridget Phillipson, celebrating with supporters at her constituency count in Sunderland, said in his victory speech that 'after 14 years the British people have chosen change'
Rishi Sunak put on a smile when arriving to vote in his Richmond constituency in North Yorkshire this morning, hand in hand with his wife Akshata Murty
The exit survey, run for broadcasters by polling guru Sir John Curtice, is not guaranteed to be exact, it has accurately reflected the outcome in recent elections.
Less than an hour before the exit poll dropped, Downing Street released a dissolution honours list - sending seven Tories and eight Labour politicians to the Lords.
They include Theresa May, Rishi Sunak's chief aide Liam Booth-Smith, Chris Grayling and former 1922 committee chair Graham Brady.
Among Sir Keir's nominations for peerages are Blair-era Foreign Secretary Dame Margaret Beckett, as well as veteran Labour MPs Harriet Harman, Dame Margaret Hodge and Kevan Jones.