THERESA May will give no further ground to Nicola Sturgeon on her flagship Brexit Bill as the SNP Government now stands alone in opposition to it following a breakthrough deal with Cardiff.

Whitehall’s view is that while the door to talks is still open, the Prime Minister’s final offer is on the table and to give more concessions to Edinburgh now would jeopardise the agreement with the Labour-run Welsh Government.

“That’s it,” declared one senior UK Government source.

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This means that if the First Minister declines to backtrack on her opposition to the EU Withdrawal Bill, then a constitutional clash between Edinburgh and London will take place as Mrs May and her colleagues are adamant the “vital” piece of legislation to produce legal certainty after Brexit will be pushed through with or without the consent of MSPs.

While the Welsh Government will repeal its own Continuity Bill, the Scottish Government now faces a legal tussle with Whitehall over its own version before the judges of the UK Supreme Court; probably in June.

The UK Government insists it has “moved significantly” since the talks began several months ago but it now believes its argument against a “power-grab” has been strengthened by the agreement of Cardiff, which in a statement accepted that significant changes to the Withdrawal Bill “that protect devolution have been secured”.

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Mark Drakeford, the Welsh Finance Secretary, said: “London'swillingness to listen to our concerns and enter serious negotiations has been welcome. In a devolved UK the respective governments need to deal with each other as equals and this agreement is a step in the right direction.”

Whitehall’s amendments to the legislation will be published later this morning ahead of what promises to be a fiery session of Scottish Questions in the Commons chamber.

Conservative ministers also feel the agreement of the Welsh Government has greatly strengthened their hand in getting the bill through the House of Lords, where the SNP has no representation.

At Holyrood, the First Minister took to social media, tweeting: “The bottom line on #EUWithdrawalBill at this stage is this - @scotparl powers on vital matters could be restricted for up to seven years without our consent. @Scotgov will not recommend consent to that - but we have put forward solutions that would form the basis of a deal.”

In a letter to the PM, Ms Sturgeon insisted clause 11 of the bill, which deals with the transfer of devolved powers after Brexit, showed an “imbalance and lack of trust” between the governments.

Her colleague, Michael Russell, in a statement to MSPs, maintained the Scottish Government’s argument that the UK legislation was a “crude power-grab”.

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The Scottish Brexit Minister flatly rejected suggestions from Whitehall sources that he had been “content” with a deal at the end of last week before being overruled by the FM.

Mr Russell suggested two possible ways forward:

*removing clause 11 from the bill so both governments could then agree, on equal terms, not to bring forward legislation in devolved policy areas while negotiations on common frameworks were taking place and

*reverting to the present system, that Holyrood should give its consent to Westminster legislating in devolved areas.

“These are practical, workable solutions to this issue that will ensure the necessary preparations for Brexit can be taken across the UK whilst protecting devolution,” he declared.

But Adam Tomkins, the Scottish Conservatives’ constitution spokesman, accused Ms Sturgeon of putting "her narrow Nationalist agenda before the good of the country".

He added: "The Welsh Government has signed up to this deal yet Nicola Sturgeon, alone, refuses because she prefers to pick a fight with the rest of the UK in order to keep her obsession with a second independence referendum alive."

Mr Russell’s two options are not acceptable to the UK Government, which believes Holyrood should not have a veto on its ability to protect the economic integrity of the United Kingdom.

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Responding to the SNP Government’s rejection of Whitehall’s offer, David Mundell said: “I’m disappointed and I have to say a bit frustrated that Nicola Sturgeon seems to have vetoed a deal with the UK Government on amendments to clause 11 of the EU Withdrawal Bill.”

Insisting “our door remains open,” he explained Whitehall was still willing to hear the SNP administration’s representations; plans are afoot to arrange a Joint Ministerial Committee in London next week.

Urging the FM to reconsider, the Scottish Secretary noted: “It would be far better to proceed on the basis of agreement and, of course, I will do everything I can to try and reach agreement but we cannot do so on the basis of changing the devolution settlement.”

The new proposed amendments to the bill are due to be debated in the Lords next Wednesday.

One peer noted that while there will be a deal of unease in the upper chamber at the Scottish Government’s continued opposition to the legislation, the UK Government “will get it through”.