THERESA May is due to flesh out her own assurances to MPs and Northern Ireland’s business leaders over the Brexit process this week as she continues to seek ones from Brussels over the Irish backstop.

After the Prime Minister schmoozed Tory MPs at the first of two Downing St drinks parties last night, she will today chair Cabinet to update her colleagues on the progress or otherwise of her Christmas diplomacy; she spoke to, among others, Angela Merkel, Emmanuel Macron, and Jean-Claude Juncker, and kept “in touch” with Ireland’s Leo Varadkar.

But as the expectation persists that MPs will reject the May Brexit Plan next week, Whitehall sources admitted senior ministers were as much in the dark about any Plan B as the public was.

It is thought Mrs May will seek to reassure MPs they will have a key input into the way forward by adopting an amendment tabled by Tory colleague Hugo Swire, which would give MPs a vote on either the UK entering the backstop or extending the transition period, should a new trading relationship with EU fail to materialise.

Mrs May is also expected to offer guarantees to Northern Ireland’s businesses that, in any backstop, they would continue to have full access to the British market.

The PM looks set to confirm what David Lidington, her de facto deputy, said during a Holyrood visit in November that Great Britain would “not diverge from the regime” of EU regulations, which Northern Ireland would abide by during the backstop; thus, there would be no border down the Irish Sea.

Yet, the “concession,” as Mr Lidington described it, has already been dismissed by the Democratic Unionists, who said: “We would be fools to accept any such assurance."

One notion doing the Whitehall rounds is that, just before the Brexit vote, Brussels will offer a last-minute concession.

Damian Green, the former Cabinet Office Minister, confidently predicted: “Clearly something is going to happen.”

Intriguingly, the UK Government is pushing for a legally binding start-date to the future partnership from December 2021; this would effectively set a 12-month deadline from the start of any backstop at the end of the transition period in December 2020.

Yet it is hard to see the EU27 agreeing to what could amount to a "blind trade deal".

In other developments:

*a new weekly Cabinet committee on “Brexit preparedness”, to be chaired by Mrs May, is expected to meet later this week;

*No 10 failed to reject the idea that the Government would try to scrap the Commons February recess and make MPs sit over weekends to get the eight outstanding Brexit bills through Parliament before exit day on March 29 - No 10 said UK ministers would “do whatever is required” to get the Statute Book ready for exit day;

*Tory grandee Lord Patten insisted Margaret Thatcher would have been "horrified" by the PM's Brexit Plan as he backed calls for a People’s Vote and

*Margot James, the Culture Minister, floated the idea of extending Article 50.