Theresa May will be expected to stand down if she loses Tuesday night’s crucial vote on her Brexit deal as heavily as predicted, Cabinet sources have said.

More than 100 Tory MPs have insisted they will oppose the deal, putting Mrs May on course to break a series of unwelcome Parliamentary records.

She launched a last-ditch attempt to win over the rebels on Monday, producing a letter from Brussels promising that the Northern Ireland backstop would be temporary and “not a threat or a trap”.

On Tuesday night Mrs May will make one final bid to change MPs’ minds when she closes the five-day debate on the Brexit deal, having already warned the Commons that “when the history books are written” MPs would be judged on whether they had “let the British people down”.

If Mrs May loses the vote - expected between 7.30pm-9.30pm depending on how many amendments are chosen by the Speaker - she is expected to make an immediate statement on her next move.

Labour said Jeremy Corbyn would call a no confidence vote in the Government “within minutes” of a defeat for Mrs May, with such a vote likely to go ahead on Wednesday. If the Government loses the vote, a general election could follow.