Nigel Farage predicted general election success for his Brexit Party if the UK does not leave the European Union after claiming victory in the European contests.
On a terrible night for the Conservatives and Labour, the pro-EU Liberal Democrats emerged as the other big winners — underlining the continuing deep divisions over Brexit in British politics.
Foreign Secretary and Tory leadership hopeful Jeremy Hunt said the dire results for the Conservatives meant the party faced an “existential risk” unless it delivered Brexit.
Meanwhile two of Labour’s most senior figures — Emily Thornberry and Tom Watson — tore into the campaign fought by Jeremy Corbyn, claiming the party had lacked a clear message and should have backed another referendum.
Mr Corbyn said: “With the Conservatives disintegrating and unable to govern, and parliament deadlocked, this issue will have to go back to the people, whether through a general election or a public vote.”
In a sign that he could consider a shift in position, he added: “Over the coming days we will have conversations across our party and movement, and reflect on these results on both sides of the Brexit divide.”
Mr Farage hailed his party’s success as he was elected in the South East, saying: “There’s a huge message here, massive message here - the Labour and Conservative parties could learn a big lesson from tonight — though I don’t suppose that they actually will.”
In a message to the Westminster parties he added: “If we don’t leave on October 31 then the scores you have seen for the Brexit Party today will be repeated in a general election, and we are getting ready for it.”
Mr Farage repeated his demand for the Brexit Party to be involved in the negotiations ahead of the Halloween deadline.
After 10 of the 11 constituencies in England, Scotland and Wales had declared, the Brexit Party had 28 seats, overhauling the 24 MEPs that Mr Farage’s former party Ukip sent to the European Parliament in 2014.
The Lib Dems, who were reduced to just a single MEP in 2014, were on 15.
Labour had 10, halved from 20, the Greens — who also enjoyed a boost from pro-EU voters — were on seven, up from three in 2014.
Plaid Cymru equalled the single seat they won in 2014.
The Tories had just three MEPs, having won 19 in 2014.
The scale of the Tory disaster was underlined by its vote share — just 9% in the 10 seats to declare, in fifth place behind the Brexit Party on 33%, Liberal Democrats on 21%, Labour on 15% and the Greens on 12%.
Mr Hunt said “we knew it was coming but still a painful result” adding there was an “existential risk to our party unless we now come together and get Brexit done”.
Liberal Democrat leader Sir Vince Cable said it had been a “brilliant set of EU results” with the party “making gains around the country with some really impressive swings in many seats”.
It was “proof that the Lib Dems are the biggest, strongest voice of Remain”.
The result in Scotland will not be formally declared until later on Monday but First Minister Nicola Sturgeon said her SNP had won “emphatically”.
She said the SNP would take three of the six available seats in a “historic victory”, adding that “Scotland has rejected Brexit again”.
The Brexit Party, who came second across Scotland, appear on course to secure one MEP, as are both the Conservatives and the Liberal Democrats.
In a sign of how embarrassing the results were for Labour in the capital, the Lib Dems topped the poll in Islington, in north London - where both Mr Corbyn and Ms Thornberry are MPs.
Shadow foreign secretary Ms Thornberry told the BBC: “We should have said, quite simply, that any deal that comes out of this government should be put to a confirmatory referendum and that remain should be on the ballot paper and that Labour would campaign to remain.”
Instead, the party would get a “kicking” because “we went into an election where the most important issue was ‘what was our view on leaving the European Union’ and we were not clear about it”.
Deputy Labour leader Mr Watson said: “Following the disastrous EU election results, Labour urgently needs to re-think its Brexit position and realign with members and voters.”
The Green Party finished above the Conservatives for the first time in a national election.
Co-leader Sian Berry said: “There is clear evidence from this of strong support for the UK remaining in the European Union, but also for tackling the causes of Brexit - the massive damage done to so many communities by austerity, tax-dodging and diminution of workers’ rights.”
The result from Northern Ireland is expected to be declared later on Monday.