THE Prime Minister “clearly doesn’t listen” to critics of her Brexit plan, her former allies in the Democratic Unionist Party said, dramatically shifting the parliamentary arithmetic against her.

After keeping Theresa May in Downing Street since the last election, and supplying the 10 votes needed to give her a Commons majority, the DUP gave her the cold shoulder.

DUP MP Nigel Dodds said he did not want to rehearse the previous promises that Mrs may had made to the Commons, the country and the DUP in private about her plans.

“I fear it would be a waste of time, since she clearly does not listen,” he said to gasps.

Although pro-Brexit, the DUP is profoundly opposed to any deal putting Northern Ireland on a different footing from the rest of the UK, something it says would weaken the Union.

However the draft withdrawal agreement promoted by Mrs May includes an Irish backstop deal that would see Ulster more closely aligned with EU rules than Great Britain.

Referring to the other 27 EU nations, Mr Dodds said the country now faced “subjection to the rules and laws of others who may not have our interests at heart”.

He congratulated the cabinet secretaries and ministers who had resigned citing their concern for “our precious Union”, and the UK would pay a £39bn divorce bill “for nothing”.

He said: “The choice is now clear: we stand up for the United Kingdom - the whole United Kingdom and the integrity of the United Kingdom - or we vote for a vassal state, with the break-up of the United Kingdom. That is the choice.”

Mrs May said she hoped to be able to continue discussions with the DUP, and insisted Northern Ireland had been a key concern throughout the Brexit negotiations.

He said: “The right honourable gentleman refers to the commitments I made in terms of Northern Ireland and the future relationship. Those commitments remain absolutely."

DUP MP Sammy Wilson also attacked Mrs May's plan, saying it would could leave Northern Ireland "economically separated" from the rest of the UK.

He said: "Even if the EU allows the UK to leave the single market, Northern Ireland will remain under single market arrangements, and any border down the Irish sea will be subject to the willingness of the EU to allow that to be avoided." 

He suggested Ulster was "being put on a platter" for "abject surrender to the EU". 

Mrs May denied that was the case, but admitted: "There will be specific regulatory alignment [for Northern Ireland], which I recognise is uncomfortable. 

"There is a question in the future, which I know has raised a concern, as to whether there will be regulatory divergence between Great Britain and Northern Ireland.

"It is possible for us, and we will make unilateral commitments to Northern Ireland in relation to that issue - because we are talking about a temporary period - of no regulatory divergence.

"The checks and controls actually relate to the degree of regulatory divergence, so if there is no regulatory divergence, obviously, that has an impact on reducing the necessity for any checks and controls.

"Crucially, the EU wanted to say that it would determine whether a good that was produced in Birmingham could be sold in Belfast. We were very clear that the EU could not determine that in the future. It will be the UK Government who make those determinations."