BORIS Johnson’s Brexit deal will “seal the fate of the Union,” Ian Blackford claimed after the UK Government’s Withdrawal Agreement Bill received Royal Assent and became law.

With just a week to go before Britain formally leaves the European Union, the SNP leader at Westminster decried how the Conservative administration had “rode roughshod over devolution” after pressing on with its legislation in the face of opposition from the three devolved legislatures.

At just after 2.30pm, Nigel Evans, the Deputy Speaker, rose in the Commons chamber to announce, to cheers from some MPs, that the Brexit Bill had received Royal Assent.

Jacob Rees-Mogg, the Commons Leader, tweeted: “To quote Edward Gibbon: ‘The first of earthly blessings, independence.’”

On a Point of Order, Mr Blackford declared: "This is a constitutional crisis."

He referred to a “completely unprecedented” situation in which the governments in Edinburgh, Belfast and Cardiff had refused consent to the Brexit Bill and yet it had still become an Act of Parliament.

"We find ourselves here today that our Parliament has been ignored, our government has been ignored and, against the expressed wishes of the people of Scotland that voted in the referendum and reaffirmed the right of the people of Scotland to determine their own destiny, that that has been ignored," insisted the Highland MP, who decried the “shutting down” of the rights of the people of Scotland.

Later, Mr Blackford denounced how Scotland now faced being “dragged out of the EU and into the Brexit abyss against its will,” harming livelihoods and jeopardising businesses.

The party leader insisted: “The Tories' toxic race-to-the-bottom Brexit plans and their contempt for Scotland and other the devolved parliaments will seal the fate of the Union. It's little wonder they are running scared of democracy in Scotland but their anti-democratic stance is unsustainable.”

He argued it was clear “beyond any doubt Scotland will never be treated as an equal partner in the UK”.

Mr Blackford insisted Scotland’s future must rest solely with its people and “not a detached and dangerous Tory Government acting against Scotland’s interests”.

Next week, dubbed “Brexit Week” by the UK Government, Nicola Sturgeon, the First Minister, is set to reveal the Scottish Government’s next steps in its campaign for securing another Scottish independence referendum.

In what promises to be a charged political atmosphere, the week at Westminster will begin with a Commons debate on the Claim of Right and end with one on Global Britain.

Next Friday, the Cabinet will meet in northern England, Mr Johnson will address the nation, Downing St will have a projected clock on its façade while Brexiteers have organised a party in Parliament Square.