Pressure is mounting on Labour leaders to change their official position on Brexit, as more MPs broke ranks to join a campaign calling for a second referendum on the deal put forward by government.
Sixteen more Labour MPs, this time all from London - which voted to remain - joined forces with Liberal Democrat leader Sir Vince Cable and two other Lib Dem MPs to warn that a bad deal risks damaging the capital for generations to come.
They said they were not seeking to overturn the Brexit decision, but to ensure the public got a say in what the UK's exit from the EU should look like.
It comes despite party leader Jeremy Corbyn repeatedly insisting that Labour does not support a second referendum, and firing Owen Smith as shadow Northern Ireland secretary for proposing one.
We accept that the country as a whole voted narrowly to leave. The government has a mandate to negotiate a Brexit deal.
The letter - signed by MPs including Mike Gapes, Wes Streeting, Stella Creasy and David Lammy - goes on to state that the terms of Brexit have never been put to the public, and would not be known until Prime Minister Theresa May returns to the House of Commons to present it later this year.
"It cannot be right that 650 MPs alone decide whether to accept the deal, without any say for Londoners or people across the country," the letter adds.
"That’s why we think it’s essential that there is a People’s Vote on the final Brexit deal, so that 65 million people can have their voices heard as well."
It follows in the wake of similar letters from Labour MPs in Wales, the Northeast and Merseyside.