Grieve amendment Brexit vote granted by Speaker John Bercow in defiance of No10

Theresa May faces a fresh Commons defeat today at the opening of the five-day debate on her much-criticised Brexit deal.

Parliament was attempting to seize the reins for the second time in two days - by ordering her to let MPs begin choosing a Plan B as early as next week.

“We will not allow the clock to be run down to ‘no deal’,” declared Tory rebel Heidi Allen.

The move follows on from the historic defeat last night when 20 Tory MPs, including 17 former ministers, seven of them former Cabinet ministers, defied a three-line whip on the hallowed Finance Bill to say no to a no-deal exit from the European Union.

David Lidington, Mrs May’s de facto deputy, accused Brexiters of peddling “fantasies” about being able to squeeze a better deal out of the EU.

He told Today: “So, the choice that people have is this deal or it is no deal or it is, as some MPs advocate, to reverse the 2016 referendum entirely.”

Mrs May tried to win back her DUP “allies” this morning with the offer of a “Stormont lock” described as a veto over any new areas of EU law and policy during the proposed backstop period. But it was dismissed by Sammy Wilson, the DUP Brexit spokesman, as “window dressing”.

This morning 22 MPs Conservative, Labour, the Liberal Democrats and Greens joined forces again for an amendment that would set a three-day deadline for the Prime Minister to come back to the Commons with new plans if, as expected, her own blueprint is voted down on Tuesday.

The move would allow MPs to formally put forward alternatives for the first time, including a People’s Vote, and the Norway and Efta “soft Brexit” options.

“We are now on very tight time tolerances to find a solution to the Brexit crisis, following the delay caused by the Government pulling the vote in December,” said former Attorney General Dominic Grieve who masterminded the amendment, which is backed by five Tory and five Labour ex-ministers.

With the Brexit deal now threatened by guerilla warfare, Mrs May tried to win back her DUP “allies” with a “Stormont lock”, described as a veto over any new EU areas of law and policy during the proposed backstop. But Sammy Wilson, the DUP Brexit spokesman, dismissed it as “window dressing”.

No 10 officials claimed the Grieve amendment was “in order” and therefore would not be voted on.

But a source told the Standard that Speaker John Bercow had decided to defy No 10 by selecting it for a vote anyway.

Cabinet minister Amber Rudd has been leading pressure in Mrs May’s top team to allow votes in Parliament designed to flush out if there is a majority for any Brexit solution. One senior minister loyal to Mrs May said: “I do not believe there is a majority for another referendum, and the Norway idea has waned. I think we could end up back with Theresa May’s deal.”

A former Tory chief whip, Andrew Mitchell, told Today that he regarded Mrs May’s Brexit deal as “humiliating”.

Treasury Committee chair Nicky Morgan, who helped organise last night’s defeat, rapped the Treasury for withholding analysis of how the deal would impact the economy from MPs.

Downing Street is banking on getting new legal guarantees from Brussels in time to win over MPs at Tuesday’s vote.