A boast by Theresa May’s deputy that Nicola Sturgeon has now abandoned her claim that the UK Government’s flagship Brexit Bill is nothing more than a power-grab has been swiftly rejected by Edinburgh.

But a generally positive meeting of the intergovernmental Joint Ministerial Committee – the first since February – has paved the way for a meeting between the First Minister and Theresa May to discuss Brexit in the next few weeks.

Following the JMC meeting in Whitehall, Damian Green emerged to declare it had been "very constructive" and "successful".

He went on to say: “You will see from principles that we have agreed…that talk of a power-grab is now behind us.

"We've agreed that obviously there need to be ways in which we preserve the UK single market so we don't damage businesses in Scotland or Wales or Northern Ireland.

"But [also] that we fully respect the devolution settlements, that we expect this to end with more powers going to the devolved administrations than they have had under the previous arrangement," he added.

However, Michael Russell, who attended the JMC representing the Scottish Government, dismissed Mr Green’s assertion on a power-grab, saying Ms Sturgeon would still recommend that Holyrood should refuse to give its consent to the EU Bill "until the power-grab is removed".

The crunch time in the constitutional stand-off is likely to be around February when the EU Withdrawal Bill, which will transpose all EU law into UK law, reaches its final stages in the House of Lords. Holyrood will be asked for its consent just before the legislation is due to end its passage in the second chamber.

If MSPs continue to withhold their consent at that stage, then Mr Russell has suggested the two governments and parliaments would be entering “trench warfare”.

After the JMC, David Mundell also hailed it as a “very constructive meeting”.

While the constitutional arguments about where powers from the EU should reside long term will continue, the Scottish Secretary welcomed agreement on the principles underlying further talks.

“We have a basis on which to take forward further detailed discussions between officials before we next meet. We’ve got a good understanding of the concerns which the Scottish Government want to feed into the negotiation process and we’ve got a basis for continuing this type of dialogue going forward. It’s a major step forward,” he declared.

The principles agreed at the JMC on how to treat powers repatriated from the EU include a commitment that any common framework would "respect the devolution settlements and the democratic accountability of the devolved legislatures".

They would "lead to a significant increase in decision-making powers for the devolved administrations" and would ensure that the competence of the devolved governments would not "normally" be adjusted without their consent.

They also stated the need to enable the UK's internal market to function while acknowledging policy differences and to ensure Britain could sign new trade deals with other countries.

Mr Mundell, who said he was about to engage extensively with the committees at Holyrood on Brexit, added: “The Scottish Parliament can be persuaded that the EU Withdrawal Bill is the right way forward; that’s what I am focusing my energies on.”

Asked about the row over Whitehall’s non-disclosure about analysis of Brexit on Scotland – last week the Brexit Department would neither confirm nor deny it had undertaken such analysis, claiming if it did so it could undermine the talks process – the Secretary of State insisted a lot of information had been shared about the impact on sectors but failed to answer the question directly.