ES News email The latest headlines in your inbox twice a day Monday - Friday plus breaking news updates Enter your email address Continue Please enter an email address Email address is invalid Fill out this field Email address is invalid You already have an account. Please log in Register with your social account or click here to log in I would like to receive lunchtime headlines Monday - Friday plus breaking news alerts, by email Update newsletter preferences

Jeremy Corbyn risks disaster in Labour’s London heartland if he refuses to help stop Brexit, a major poll reveals today.

Voters say they would punish the party at the next general election, allowing the Conservatives to pull ahead in the capital for the first time since 1992.

Tottenham’s Labour MP David Lammy said the YouGov survey of more than 2,500 Londoners showed Mr Corbyn risked “fatally harming our chances at the next election” if he failed to oppose Brexit in Parliament.

Labour triumphed in London with a record 54.5 per cent of the vote in the 2017 election. The Conservatives managed only 33 per cent. The poll suggests that Labour is already losing support amid divisions over Brexit, with its share now reduced to 40 per cent and the Conservatives on 35.

But if Labour MPs failed to oppose a Brexit deal in the Commons, for example if Mr Corbyn gave them a free vote, the party’s London share would plummet to 30 per cent, with the Conservatives rising to 37 per cent.

If a majority of Labour MPs supported a Brexit agreement, Labour’s vote would fall even further, to 28 per cent.

The big winners if Mr Corbyn is seen to sit on his hands while Brexit happens would be Vince Cable’s Liberal Democrats, whose vote share would soar from a meagre 10 per cent to 24 per cent.

Londoners are even more opposed to Brexit than they were in 2016 when the referendum took place, according to the poll commissioned for the People’s Vote campaign, which advocates a second referendum to let the public choose between Remain and the Prime Minister’s withdrawal agreement.

The capital backed Remain by 60 per cent to 40 per cent in the referendum, but this would grow to 65 to 35 if Londoners had their say again. Londoners oppose Mrs May’s proposed Brexit agreement by 71 to 29 per cent. They are also at least three times more likely to be pessimistic than optimistic about prospects for living standards, the NHS, the economy and young people under Brexit.

Mr Lammy, a leading People’s Vote supporter, said Mr Corbyn could no longer afford to sit on the fence.

“On the biggest issue of our generation, Labour risks complicity in the Conservative Party’s historic mistake,” he said. “We have the opportunity to save our country from catastrophe and so we should seize it with both hands.

“If we do not, this poll shows it is Labour, not the Tories, that will be punished at the ballot box.

“We not only risk fatally harming our chances at the next election, we will betray millions of voters, particularly the young who saw us as a beacon of hope.”

Two top Conservatives have called for a referendum at a rally in London.

Former universities minister Sam Gyimah said: “The poverty of the choices now before Parliament owe much to the stubborn, narrow and opportunistic path taken by both the Government and Opposition.”

Former Tory chairman Lord Patten said: “We got into this miserable shambles because of a referendum and it will take another to get us out of it.”