TWENTY years on from Scotland voting Yes to a Scottish Parliament, Holyrood is at the centre of a “constitutional crisis” that could, for the first time in its history see it overruled by London.

That’s the warning from some of the country’s politicians, who say tonight’s vote on the UK Government’s EU (Withdrawal) Bill could ride roughshod over the will of the voters who backed devolution in 1997.

The Scottish Government’s Brexit Minister Michael Russell said: “There is already a constitutional crisis here. If they push on without consent it will become deeper and much more intense. They would be legislating for both Scotland and Wales without our consents and that would be the first time that has happened in 20 years.”

Though the SNP, Labour, the LibDems and others have said they’ll vote against the Tory Bill in Westminster tonight, Theresa May’s £1 billion deal with the DUP after the election should give her the numbers in the Commons to guarantee it safe passage towards the next parliamentary stage.

Remainers in her party have indicated that they won’t rebel just now, but will rather wait for that next committee stage where MPs go through the Bill line by line.

If, as looks likely, the Bill passes, and there are no substantive changes, then it would more than likely be rejected by the parties in Holyrood, which could then lead to Whitehall, for the first time ever, being forced to legislate on behalf of the Scottish Parliament without the backing of MSPs.

Tomorrow, the Scottish Government is due to set out a legislative consent paper, setting out how the Bill should change if it wants to receive the backing of MSPs in Holyrood.

Not that MSPs are being wooed particularly hard by the Tory government. One SNP member of the Scottish Parliament’s Brexit committee pointed out that today they were to meet and question Brussels’s chief negotiator Michel Barnier, and yet, despite repeated requests, David Davis has so far refused to meet.

The opposition have fears over the power granted to the government in the Bill, both on devolution and the so-called Henry VIII power that will allow ministers to make changes to laws without the oversight of parliament. Tories insist this is purely technical, and necessary to change the thousands of regulations that need to be altered for Brexit.

In Scotland, the SNP says the Bill, as it stands, will give London power over policy areas after Brexit, that should be devolved to Scotland.

SNP foreign affairs spokesman, Stephen Gethins called for all of the other Scottish MPs to back his party’s plans to block the Bill.

“On the 20th anniversary of the 1997 devolution referendum – the day Scotland voted to reconvene the Scottish Parliament – SNP MPs in Westminster will stand against the Tories’ EU Withdrawal Bill that undermines the very foundations of the devolution settlement.

“SNP MPs will work across the political divide to challenge the Withdrawal Bill and its attempts to centralise power in London over issues that are already devolved to the Scottish Parliament, including agriculture and fishing.

“’Re-reserving powers’ coming from Brussels is the Tories’ polite language for a power grab,” the North East Fife MP argued.

He added that the Scots could hold the key to stymieing the repeal Bill. In an interview this week, the Scottish Tory leader Ruth Davidson said she feared Brexit would be an “economic hit, we don’t bounce back from”.

In June she vowed to scupper a hard Brexit, saying her 13 MPs would vote “entirely as they believe that they should”.

It seems unlikely, however, that they will rebel tonight.

Gethins said: “If the new Scottish Labour MPs could persuade their colleagues to get behind the SNP and deny the EU Withdrawal Bill a second reading - something that the Westminster group have hinted at - they would find allies across the Chamber.

“Scotland’s 13 Tories, whose leader backed the single market last year, would then be all that was needed for a majority. That would provide a soft landing and give businesses and the rest of us the certainty needed.

“The Tories’ extreme Brexit was rejected in the General Election and Scottish MPs this week have a crucial role to play in standing up for our economy and defending our Parliament.”

Writing in yesterday’s Telegraph, Davis said the opposition to the Bill was often vacuous: “Any broad attempt to block the Bill, without any sense of a viable alternative, is simply an attempt to thwart the democratic process.”

“So, as my colleagues in the House of Commons proceed through the voting lobbies tomorrow, they must remember what they are voting for.

“They are not voting on whether or not we leave the EU. That decision was made by the British people last June. Nor are they voting for the terms of our exit. Those will be agreed as we proceed through our negotiations with the EU. What they are voting on is how we leave: whether our withdrawal is smooth and orderly, or chaotic and uncertain.”

Meanwhile, Brexiteers close to Davis, have said he’s not really incompetent, despite what others say. They have accused Brussels of “drip-feeding poison” to business chiefs, civil servants and friendly journalists in a bid to undermine the UK position.

Tory sources told the Sun on Sunday that allies of European Commission president Jean-Claude Juncker have formed a “black ops” unit to attack Davis.

One insider said: “It’s clear their strategy is to weaken the UK’s position by making us look incompetent, weak or out of our depth.

“Hardly a single meeting has taken place without a damaging story about the British delegation appearing.

“More often than not it’s an over-spun account of a private discussion. Sometimes they are just smears.”