THERE were calls for David Mundell to resign as Secretary of State for Scotland yesterday over his failure “to lift a finger to protect our national interests,” in the Brexit negotiations.

It came as MPs were told to expect a long day next Tuesday, possibly sitting until 3am on the Wednesday morning, as the government tries to undo all 15 amendments made to the EU Withdrawal Bill by the Lords.

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But it looks as if there will still be no changes made to the legislation’s contentious “power grab” clause.

Clause 15, formerly clause 11, sees some powers held by the EU being repatriated to London rather than Edinburgh, despite being in devolved policy areas.

These include areas like farming, fishing, environmental protections, food standards and food labelling.

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Last month that power grab led to SNP, Labour, LibDem and Green MSPs in Holyrood all declining to give the EU Withdrawal Bill consent.

In a heated exchange in the Commons, Edinburgh East MP Tommy Sheppard questioned the Tory minister’s competence.

“I can forgive some members of the Cabinet their ignorance in not understanding the effect of their policies on the devolution settlement, but that is not a quality that we expect from the Secretary of State for Scotland,” Sheppard said, accusing Mundell of a “particular form of arrogance” for trying to “force through a position that is supported by only one of the five political parties in Scotland and by less than one quarter of the Members of the Scottish Parliament”.

Mundell was, he added, the “first Secretary of State for Scotland in history who seeks to lessen the control of the Scottish people over their own affairs”.

“Will he now stand down and make way for someone who will respect the wishes of the Scottish people and respect the national Government of Scotland?” Sheppard asked.

Mundell declined to resign, and accused the SNP MP of being obsessed with independence.

Sheppard, the Tory said, had “let the cat out of the bag with his final words. Scotland has two Governments. In 2014, Scotland voted to be part of this United Kingdom, and I will continue to stand up and defend Scotland’s place in it”.

Resignation was in the air in Westminster yesterday, with rumours swirling around that Brexit Secretary David Davis was on the brink of quitting after being undermined by the Prime Minister on the issue of the Irish border.

The disagreement was over the government’s Brexit “backstop” proposal, which is due to be outlined at the Cabinet’s Brexit sub-committee today.

It is, in effect, a contingency plan that would create a “temporary customs arrangement” with the EU if the government fails to agree a permanent solution before Brexit day next year.

It will prevent the need for a hard border between Northern Ireland and the Republic of Ireland until a final customs deal that satisfies London, Brussels and Dublin, can be reached.

The EU had initially proposed a backstop that would have seen the whole of the island of Ireland effectively treated as one country with the same regulations as the rest of Europe. But the UK said creating a border between Northern Ireland and the rest of the UK was not acceptable.

Instead, the UK is proposing a “backstop” option which will see the whole of Britain temporarily aligned with the EU’s customs union after December 2020 – when the 21-month post-Brexit transition period ends.

Crucially, and despite Brexiteer anger, the document doesn’t contain an end date for the backstop.

A leaked copy of the proposal was seen by the BBC, who said it would even see the UK agreeing to “respect the remit” of the European Court of Justice and interpret EU laws and directives “consistently”.

One Brexiteer told the corporation that it was a “Hotel California” scenario where the UK never fully leaves the EU.

Davis and other Brexiteers believe the backstop would commit the UK to staying in the customs union and single market for good.

They believe it will make it impossible to have further negotiations over a future trading relationship with the EU.

The latest clash between the Prime Minister and her Brexit secretary comes after the pair also disagreed about the timing of publication for a white paper on the government’s Brexit stance.

Davis was keen to produce a detailed document before the European council at the end of June. May, however, is more cautious.

May was asked by Jeremy Corbyn at Prime Minister’s Questions when it would be published.

She did not answer. The Labour leader also asked her to confirm that it remains her plan to “leave the European Union in March 2019 and complete the transition by December 2020”.

May said it did.

During the session, the SNP’s Westminster leader, Ian Blackford referred to reports over the weekend that civil servants had drawn up a “Doomsday” scenario looking at the worst possible outcome for the UK if it crashes out of Europe without a trade deal.

Officials suggested just two days after exit day there would be shortages in Scottish and Cornish supermarkets, which would be followed by shortages of medicines and petrol.

Blackford said: “Supermarkets running out of food within days, hospitals running out of medicines within a fortnight, petrol reserves dwindling after just two weeks: these are the concerns of UK Government officials.”

“Does the Prime Minister understand the catastrophic negotiating position she has cornered herself into?” he asked.

The Prime Minister told Blackford that supermarket chains north of the border wanted Scotland to “remain part of the United Kingdom”.