DAVID Mundell’s threat to quit yesterday – the second time he has done so in a week – pushed Theresa May and Scotland closer towards a no-deal Brexit.

The Tory MP has reportedly told the Prime Minister he will not accept the implementation period – the time between Brexit day in March next year and the day the UK fully leaves Europe and new arrangements kick in – being delayed unless it includes an opt out for the Common Fisheries Policy (CFP).

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May and the EU have already pencilled in the end of December 2020 as the end of transition, the purpose of which is to allow the country time to prepare. But at this week’s summit the UK said it was considering pushing that back.

May suggested it could only be a “matter of months” but other reports floated the possibility of it lasting until December 2021. This would, crucially for Mundell, be after the next Holyrood elections, where his leader Ruth Davidson is hoping to make gains in the north-east.

Britain being bound by EU rules until then would mean fishermen would be restricted by quotas set by the CFP, but would not have any input in those discussions.

That could mean angry Scottish fishermen, who overwhelmingly backed Brexit, could be trapped by the CFP, without any say over quotas for another three and a half years.

Bertie Armstrong, leader of the Scottish Fishermen’s Federation, has said that would be “unacceptable”.

Mundell told the BBC: “There isn’t a specific proposal for extending the transition period for our departure from the EU. What I want to be quite clear is that we are still leaving the CFP at the end of 2020.

“I think it is a very important thing for fishermen here in Scotland to know and understand, that that is the date we are leaving the Common Fisheries Policy.”

Mundell added that his intervention was about making sure that the plight of Scottish fishermen was being thought of by Brexit negotiators.

He said: “Leaving the CFP is an essential part of leaving the EU. Many people here in Scotland voted to leave the EU because they wanted to leave the CFP. People who were still Remain voters, even they would admit the CFP has been bad for Scotland, bad for the UK, and they want to leave.

“I want to be absolutely clear that we are leaving the CFP on the date that was set out at the end of 2020, and that we are an independent coastal state for the fisheries council in December 2020 and that remains my priority.”

It seems unlikely that the EU would grant some form of “partial” extension to the implementation that didn’t include all of the acquis, the body of common rights and obligations binding on all EU countries.

But Foreign Secretary Jeremy Hunt warned that an extension to the implementation period could be crucial to stop the UK crashing out of Europe without a deal.

Hunt told the BBC that compromises would have to be made.

He said: “There is a situation in which you’ve negotiated a free trade agreement and it’s going to take a few months more to implement, but months not years, when it might be helpful to have the ability to extend the transition period.

“There’s all sorts of difficulties and all sorts of compromises that people of all sides are making, but the fundamental point is that we are leaving the EU at the end of March next year and we’re leaving it with the letter and spirit of what people voted for in the referendum.”

The SNP MEP Alyn Smith told The National: “Mr Mundell has been a Toom Tabard throughout all of these negotiations and only now is he trying to spare his blushes as he realises, as we all have years since, that Scotland is going to get a bad deal from any Brexit.”