OPPOSITION parties have continued to pile the personal pressure on David Mundell, branding him "Scotland's invisible man in the Cabinet".

Paul Sweeney, the Shadow Scotland Minister, claimed the Secretary of State had "failed to stand up" for Scotland's devolution settlement, despite being the longest serving member in one role in Theresa May's Cabinet.

But Mr Mundell hit back, branding Labour "just Nicola's little helpers" as he attacked the "once proud unionist" Scottish Labour Party for "repeatedly voting" with the SNP in Holyrood.

Speaking during Scotland Questions in the Commons, Mr Sweeney said: "I feel I ought to congratulate the Secretary of State on achieving a new milestone as the longest serving member in one role in the Prime Minister's Cabinet, though I fear it may be a virtue of his invisibility rather than his invincibility…

"The Secretary of State is failing to stand up for Scotland's interests when it comes to shipbuilding and his 12 Scottish Tory colleagues and himself have failed to stand up for Scotland's devolution settlement.

"So, will he use the influence he should have developed over these last few years and condemn his Government's handling of the devolution settlement, demonstrating he isn't just Scotland's invisible man in the Cabinet?" asked the MP for Glasgow North East.

Mr Mundell responded by saying: "What I condemn is the once proud Unionist Scottish Labour Party repeatedly voting with the SNP in Holyrood. What they've become I'm afraid is just Nicola's little helpers."

The SNP’s Joanna Cherry told MPs that the UK Government’s Chequers Plan “rode roughshod” over the Scottish Parliament. She said: “Scotland’s economy is heavily reliant on services and thousands of my constituents work in the services sector, yet the Prime Minister is determined to make a deal, taking services out.”

The Edinburgh MP asked the Scottish Secretary: “Has he worked out yet what the impact of the PM’s decision on the Scottish economy and what is he going to do about it?”

Mr Mundell said the heart of the Scottish Government’s document, which was “fed in” to the Chequers summit, was that the SNP administration did not want the country to leave the EU.

“What the PM is focused on is leaving the EU on the basis that does best for British business but also respects the outcome of a referendum of the whole of the United Kingdom.”

After the SNP’s Hannah Bardell also accused Mr Mundell of being “invisible” and “ineffective” in his role and called for him to resign, the Scottish Secretary accused her of “reheating the same old stuff” and declared: “At the heart of this is the SNP don’t accept and don’t like the representations I make on behalf of Scotland; that is to keep Scotland in the UK.”

His Tory colleague Steve Baker, who resigned earlier this week as Brexit Minister in protest at Theresa May’s Chequers Plan, denounced the “ludicrous theatrics” of the SNP. “They are a disservice not only to the people of Scotland but to the people of the whole of UK for the detrimental effect they had on the passage of the EU Withdrawal Act,” he said.

Mr Mundell went on to accuse the Nationalists of not being interested in Britain’s withdrawal from the EU, claiming: “Brexit has been weaponised purely to take forward the cause of independence and have another independence referendum.”

Later, Whitehall rubbished Ms Sturgeon’s claim of a “power-grab” in the Government’s new Brexit Act. A UK Government insider said: A UK Government source said: “There is no ‘power-grab,’ it is just an SNP invention.

Nicola Sturgeon expanded her ministerial team to record numbers to handle her Government’s additional responsibilities. And now the Scottish Government have taken over a new office block to house the extra civil servants they need.

“Her phoney cries of ‘power-grab’ sound sillier by the day,” he added.