David Davis has written a last-gasp letter to MPs to try to prevent a damaging defeat on the Brexit Bill tonight, as another Cabinet minister promised “concessions”.

The Brexit Secretary also tabled a Commons statement to try to win over Conservative rebels in a crucial vote that could give MPs the power to delay Brexit.

However, those Tory backbenchers have indicated they will not back down – and have insisted they have the numbers to inflict a first defeat on the EU Withdrawal Bill.

The consequences would be grave for Theresa May, a day before the EU summit to confirm “sufficient progress” for the withdrawal talks to move onto future trade, stoking fears among EU leaders that she is too weak to deliver on Brexit.

Early today, Labour confirmed it would vote with the rebels, to give “Parliament a proper say on the Brexit deal”. Keir Starmer, the party’s Brexit spokesman, tweeted: “The terms of our future are not for the Government alone to determine.”

The Prime Minister has already conceded to MPs a vote on the final Brexit deal and a Bill to implement the withdrawal agreement to follow, which could be amended.

Theresa May asked about Brexit scrutiny in light of Telegraph 'mutineer' front page

However, she has insisted it will be a “take it or leave it” offer – meaning the UK would crash out of the EU without a deal in March 2019, if hers is rejected.

Tonight’s showdown is designed to ensure it is a truly “meaningful vote” by giving MPs a veto over the terms and timing of withdrawal – to delay it potentially, if no satisfactory deal is reached.

Dominic Grieve said on Tuesday: “It could be possible for Parliament to say to the Government “I’m sorry I don’t think you have negotiated a good enough deal”.

“If our European partners are prepared to continue negotiating, that might also be possible. We just don’t know.”

Today, he again insisted he would stand firm – even after Mr Davis’ rushed statement – accusing the Government of a “dialogue of the deaf”.

“They need to listen to the point that is being made and they need to respond to it,” he told Sky News.

Justine Greening, the Education Secretary, hinted at further moves to avert defeat later today, when she twice referred to “concessions” in a radio interview.

“What we have done is genuinely listen to the debate that has happened in Parliament,” she told the BBC’s Today programme.

And she added: “We are going to make sure that, through the concessions today, we continue to command the support of Parliament.”

Mr Davis is understood to have penned his letter to MPs around 5.30am today, setting the scene for a vote expected around 7pm.

In his statement, he promised MPs “a vote on the final deal in parliament as soon as possible after the negotiations have concluded.

He wrote: “This vote will take the form of a resolution in both houses of parliament and will cover both the withdrawal agreement and the terms for our future relationship.”

Eloise Todd, the chief executive of the pro-EU Best for Britain organisation, criticised the statement as “not worth the paper it is written on”.

“The announcements in it have been reheated more times than an old microwave meal,” she said.