NICOLA Sturgeon has accused Ruth Davidson of swapping her principles for a place in the House of Lords after she quietly dropped her threat to resign over Brexit and Northern Ireland.

The First Minister took a swipe at the Tory group leader, who is due to become a peer after she leaves Holyrood at May’s election, after the pair clashed at FMQs.

Ms Davidson peppered Ms Sturgeon with questions about her husband’s controversial evidence to the Holyrood inquiry into the Alex Salmond affair.

Later, Ms Sturgeon reminded her opponent of a letter she wrote to then Tory Prime Minister Theresa May in October 2018 with then Scottish Secretary David Mundell.

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The then Scottish Tory leader and Mr Mundell suggested they could resign if Brexit led to a differentiated settlement for Northern Ireland, undermining the Union.

They wrote: “Having fought just four years ago to keep our country together, the integrity of our United Kingdom remains the single most important issue for us in these negotiations.

'Any deal that delivers a differentiated settlement for Northern Ireland beyond the differences that already exist on all Ireland basis (eg agriculture), or can be brought under the provisions of the Belfast Agreement, would undermine the integrity of our UK internal market and this United Kingdom.

"We could not support any deal that creates a border of any kind in the Irish Sea and undermines the Union or leads to Northern Ireland having a different relationship with the EU than the rest of the UK, beyond what currently exists."

This week, the UK Government agreed a deal with the EU on the border between Ireland and Northern Ireland which would see the latter subject to a unique regime within the UK.

Ms Sturgeon said: “I will quote exactly what Ruth Davidson said. 

“She said that she ‘could not support any deal that ... leads to Northern Ireland having a different relationship with the EU than the rest of the UK, beyond what currently exists.’ “Apparently, that ‘would undermine the integrity of our UK internal market and this United Kingdom.’ 

“I can only speculate that it is amazing what the offer of a seat in the House of Lords can do to change somebody’s opinion.” 

A Tory source said it would be hard for Ms Davidson to resign as leader as she'd already done so in 2019, when she cited differences with Boris Johnson over Brexit.

Earlier, in response to Green MSP Patrick Harvie raising concerns over Brexit disrupting the supply of medicines between the EU and UK after this year, Ms Sturgeon said she was deeply worried about the last-ditch trade talks floundering and the prospect of no deal.

She said: “I am deeply and increasingly concerned about the lack of clarity over the arrangements that will apply at the end of the Brexit transition period, in only a matter of weeks. 

“We are exactly a year on from the general election, when the Prime Minister said that his deal was ‘oven-ready’. Now, here we are, not knowing whether there will even be a deal. 

“If there is a deal, it will be the bare bones and a minimalist one, and it will do real damage to the Scottish economy and society. I am deeply concerned about that.”

She said plans were in place food a six-week stockpile of medicines, medical devices and clinical consumables, as well as a steady supply of Covid vaccine after January 1.

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Mr Harvie said afterwards that Brexit and Covid-19 would be a “perfect storm” for the NHS in January, traditionally the busiest time of the year for the health service.

He said: “Brexit is being imposed on Scotland against our will, but it is incumbent on the First Minister to ensure that our NHS can cope. We need urgent assurances that access to vital drugs and PPE will not be inhibited by this reckless Tory decision making.”