THE CABINET has backed Theresa May's draft Brexit agreement despite anger from backbench Tory and DUP MPs.

The consensus was announced by the Prime Minister outside Number 10 on Wednesday evening after a marathon five-hour meeting with her ministers.

May said the "collective decision" was to back the controversial plan.

She admitted there would be "difficult days ahead".

"This is a decisive step which enables us to move on and finalise the deal in the days ahead.

"These decisions were not taken lightly but I believe it is a decision that is firmly in the national interest."

May added: "I firmly believe, with my head and my heart, that this is a decision which is in the best interests of the United Kingdom."

There was anger after reports suggested May had conceded on her red lines and agreed to different regulations for Northern Irleand and the rest of the UK. 

There was specualtion that David Mundell, the Secretary of State for Scotland was on the cusp of resigning, after he added his name to a letter from all Scottish Tories demanding the Prime Minister take Britain out of the Commons Fisheries Policy by the end of 2020.

He had also previously said he could not support any different arrangements for Northern Ireland as they would "undermine the integrity" of the UK.

Shortly after May's statement, Mundell made clear he was staying put.

"I am absolutely part of the Cabinet because I am satisfied with the deal," he said leaving Number 10.

The move clears the way for a special Brexit summit in Brussels - probably on November 25 - for EU leaders to approve the deal, followed by a crucial Commons vote in which MPs will hold Britain's future in their hands.

But Brexiteer discontent has raised expectations of further letters of no confidence in May from Tory MPs, with a total of 48 needed to trigger a vote on her position.

Sources within Westminster said the delivery of letters to the chair of the backbench 1922 Committee Sir Graham Brady was "imminent".

First Minister Nicola Sturgeon was not impresssed with the deal. In a statement, the SNP leader said it was "obvious" that May "can barely unite her cabinet on this deal, and ‎it is also increasingly clear that she will struggle to get a majority for it in Parliament. "

Sturgeon added: “In these circumstances it is more important than ever that we are not faced with a false choice between a bad deal and no deal. 

“No one should be effectively blackmailed into a choice between the frying pan or the fire."