SCOTTISH Secretary David Mundell has vowed to defend Scotland’s place in the UK until his “last breath”. He emphasised the strength of his feeling under questioning from SNP MP Patrick Grady during Scottish Questions in the Commons, when he was accused of “presiding over a power grab”.

Mundell has told the Prime Minister he would be prepared to step down if a Brexit deal creates a political division down the Irish Sea.

Grady said the Scottish Tories “have never wanted the Scottish Parliament to succeed and are using Brexit to undermine it”.

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The Scottish Secretary responded: “He [Grady] and his colleagues want to break up the United Kingdom. I will defend our United Kingdom until my last breath.”

Mundell then doubled down on his ultimatum over a Brexit agreement that could in any way separate the UK.

“I make no apology for making absolutely clear that the integrity of the UK is a red line for me and my Scottish Conservative colleagues in any deal on leaving the EU,” he said. “The position is exactly the same for our Prime Minister.

“I know those on the SNP benches’ preference would be a Brexit of the most disruptive kind, which they say is best able to take forward their cause.”

Mhairi Black also scrutinised Mundell, pressing the Tory on the devolution of immigration powers to Holyrood.

The SNP MP said the Migration Advisory Committee “accepts the dangers to Scotland’s labour force and economy under the current UK system”.

She continued: “Sixty-four per cent of Scottish voters now want to see immigration policy devolved to the Scottish Parliament.

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“Given that we’ve seen the reality of the cruel system the UK Government has implemented, why not give the Scottish Parliament the right to do things differently?”

Mundell said: “These matters were considered in depth by the Smith Commission, it was agreed that immigration would not be devolved.

“And at the recent CBI Scotland dinner, which was attended by the First Minister, the director general of CBI in Scotland made clear that business in Scotland did not support the devolution of immigration and having a separate immigration policy in Scotland.”