A former Brexit Minister has warned that more than 40 Tories are prepared to side with Labour to vote down Theresa May’s EU deal.

Steve Baker, who quit the Government over May’s Chequers agreement last week, made the threat in the Commons this afternoon as he attacked the PM’s negotiating stance.

If Baker’s numbers are accurate, the UK could be set to crash out of the EU without a deal in March 2019.

As Baker was piling the pressure on May, another Tory MP gave her something to smile about when he dramatically withdrew his call for her to resign during a party meeting.

Simon Clarke, MP for Middlesbrough South, told a gathering of Tories – including May – that putting in a letter calling for a vote of no confidence in the PM was the “wrong decision”.

But the withdrawal of Clarke’s letter will offer little reassurance to May that she can get her Brexit plans through Parliament after Baker’s warning.

Speaking in the Commons, Baker predicted the SNP and Labour would both vote against any agreement for their own interests.

He went on: “That means, therefore, that this is a deal, whether people like it or not, however impartial they may be, they must bring forward a deal which can be voted through by the Conservative Party.

“The number 40 [Hard Brexiteers] has been banded around in this House in the last few days, and I’m sorry to say, and it gives me no pleasure to say it, but the thing I have to say is – and the rest.

“People who have said the number 40 are not out by a fraction when they come to consider the number of Members who don’t like this deal on these benches and are willing to vote in line with this dislike, they are out by a factor, not a fraction.”

Baker’s key objection to the Chequers proposal is that it would see the UK following a common rulebook with the EU on goods and agri-foods.

While this approach would help maintain frictionless trade in these areas, critics of the plan believe it would see the UK as rule-takers from the EU with no say over their creation.

“No one should plan on a high-alignment deal…going through this House,” warned Baker.

While those concerns are shared by Clarke, he said now was not the time for leadership election as he withdrew his call for a vote of confidence in the PM.

Clarke was given hearty pats on the back by MPs after the meeting of Tory MPs, with one remarking it was the most remarkable scene he had witnessed at a 1922 Committee.

When asked how May had reacted to the news, he replied: “She doesn’t buckle under pressure, and doesn’t revel in the good moments.”

A vote of no confidence is triggered in the Conservative leader if 48 MPs put in letters calling for a ballot, and Clarke – who is deeply unhappy with the Chequers agreement on Brexit – submitted his last Tuesday.

But facing the Prime Minister, Clarke withdrew his call for her to go, saying: “It was the wrong decision.”