THE Tories have returned to the “anti-Scottish” days of Margaret Thatcher, the SNP leadership has claimed in bitter exchanges at Westminster.

By contrast at Holyrood, the Scottish Government will today try to seek consensus by restarting cross-party talks in a bid to defuse the mounting constitutional crisis over Brexit.

In an at times acrimonious Commons debate, Ian Blackford, the Nationalist leader, launched into a blistering personal attack against David Mundell, the Scottish Secretary, whom he suggested was “yellow” for not speaking in the three-hour debate.

Declaring how the minister had no credibility, the Highland MP told MPs: “He fails to stand up for Scotland as a country, fails to stand up for our Parliament, he sees us as subservient…That’s why the Secretary of State needs to go. He is quite simply unfit for the office he holds.”

As the atmosphere became more heated, Mr Blackford looked over to the Government benches and accused the Secretary of State of “stabbing the Scottish Parliament in the back,” declaring: “Come on, up you get.”

After John Bercow, the Speaker, sought to calm things down, Mr Mundell, to ironic cheers from the SNP benches, took to the despatch box and said: “This speech, I suppose it can be called that, is not worthy of a response from me in the tone that he has set out. He calls for respect but focuses entirely on the personal in his comments.

“This may be a performance for his colleagues and his core voters, it doesn’t impress Scotland,” declared Mr Mundell to Conservative cheers.

One Tory source later branded the SNP’s attacks as “dire stuff”. He added: “They have no proper argument and that’s why they are resorting to cheap, personal attacks.”

The bitter exchanges came after last week’s dramatic scenes when Mr Blackford was ordered from the chamber and was followed by a mass walkout by his fellow Nationalist MPs in protest at the UK Government’s pressing ahead with the EU Withdrawal Bill in the face of Holyrood’s opposition.

SNP MP Martin Day suggested Whitehall’s action has sparked a strong sense of outrage from his constituents, previously witnessed following the poll tax, and he suggested Scotland had now reached a “tipping point”.

Mr Blackford claimed the devolved settlement had been “emasculated by an anti-Scottish Government,” which had used its majority in England to perpetrate a “power-grab” from the Scottish Parliament.

He called for the UK Government to bring forward emergency legislation to scrap the bill’s Scottish clause but Mr Mundell and his colleagues have made clear, after making what they regard as significant compromises, they are not willing to move any further to allow a Holyrood veto over policy aimed at protecting the UK’s internal market.

Tory backbencher Simon Hoare pointed out how Lord Sewel, one of the architects of devolution, had made clear the UK Government was not enacting a power-grab because sovereignty rested with the UK Parliament.

Referring to the convention that bears his name, Lord Sewel earlier told the BBC: "There is that 'not normally' phrase in the convention which does clearly recognise the possibility that something quite out of the ordinary would happen, which would mean the UK Parliament would be required to legislate in a devolved matter even without the permission of the Scottish Parliament.

“We're all pretty well agreed that Brexit and leaving the EU is a major constitutional adjustment. We don't live in normal times, in other words.”

At Holyrood, Michael Russell will today urge the other Holyrood parties to work on a “common approach” to defend the role of the Scottish Parliament.

The move coincides with SNP MPs threatening to disrupt business at Westminster to delay Brexit, something which could fracture the previous consensus in Edinburgh.

The Scottish Government's Brexit Minister told the Herald: “I remain committed to dialogue with all the parties and to talking with the UK Government.

“If there is a solution to be found I am open to ideas from anyone - including the Tories - but I am not sitting passively back waiting for that. That is why I will be inviting all parties to keep talking with the Scottish Government.”

At Westminster, a Commons showdown on the Brexit Bill was set for Wednesday after the Government suffered a heavy defeat in the Lords over giving MPs a "meaningful vote" on the final Brexit deal; voting was 354 to 235, a majority of 119.

Given Theresa May's working majority is just 10, then tomorrow's vote in the Commons will be on a knife-edge.