NICOLA Sturgeon has made clear the SNP will not back Theresa May’s Chequers Plan as it is “nowhere near good enough” to protect Scotland’s economic interests.

The First Minister, in London to attend events to mark the centenary of the RAF, insisted that she and her colleagues would continue to stand up for the “common sense” approach, which was to back Britain staying in the European single market and customs union.

Her remarks came as Theresa May chaired a meeting of her new-look Cabinet in Downing Street after which she tweeted: "Productive Cabinet meeting this morning - looking ahead to a busy week. And sending our best wishes to @England for tomorrow!"

Asked on BBC Radio 4’s Today programme if she could support the Prime Minister’s compromise proposal, Ms Sturgeon said: “Not on the basis of the plan as it stands. I described it at the weekend as a step forward in the sense that there appears to be more realism than we have heard from the UK Govt to date although that’s not really saying much to be honest.

“We don’t yet know whether it’s acceptable to the EU, it still seems to be cherry-picking, trying to divide the four freedoms. It looked horrendously complicated and, of course, it excludes services, which make up almost 80 per cent of the Scottish economy, and the UK economy for that matter, and a third of our exports.”

The FM denied the assertion that leaving the EU meant quitting the single market and customs union, arguing that that was not on the ballot paper in the 2016 referendum.

She explained: “If you look at the arithmetic in the House of Commons; first of all, before we think about the position across the country, I don’t think there is, in fact I’m convinced, there’s no majority for no deal. After the events of the last 24 hours or so it’s highly questionable whether there’s a majority for the Chequers Plan as it stands...I will not have my party vote for something that I know would be more damaging than is necessary to the Scottish economy.”

Ms Sturgeon described the Chequers Plan as a “step forward” from where the UK Government was a couple of weeks ago but it was “nowhere near good enough to protect our vital economic interests”.

She denied that a refusal to back Mrs May’s plan would lead to a hard Brexit. “I have been consistent, the SNP has been consistent, in saying we don’t want to leave the EU but if the UK is leaving the EU, that’s the least worst outcome.

“All of the economic analysis backs that up. This is the point at which those of us who believe that would be the least damaging outcome have to stand up and argue the case for that and that’s what the SNP will do.”

The FM stressed how she supported retaining free movement for people and services, saying: “The demands of the Scottish economy and again that’s true of the UK economy,[and] because of the differing demographics of Scotland it’s more true of the Scottish economy, is that we need to continue to attract the best and brightest talent from elsewhere; this is an economic imperative for Scotland.

“So I am not going to vote for something that would damage not only the interests of the economy now but for decades to come.”

She added: “We will continue to stand up for the compromise we think is right and stand up for common sense and the more people we can persuade to do that, the more chance we’ll get of an outcome that does reflect common sense.”

Meanwhile, in the fall-out to the resignations of Boris Johnson and Davidson and the consequent Cabinet reshuffle, Tory grandees swung behind Mrs May, urging colleagues not to trigger a leadership challenge.

Lord Howard, the former Conservative leader, warned against a bid to oust the PM, saying: "I do think that it would be extremely foolish and extremely ill-advised for anyone to send in letters to mount a motion of no confidence in the Prime Minister.

“I'm delighted, that good sense seems to be breaking out."

Sir Michael Fallon, the former Defence Secretary, asked if he thought the PM would face a leadership challenge, said: "No I don't. I think, over all, colleagues should think very, very carefully about that. That's the last thing we need at the moment.

"We now have a plan. There is now an agreed plan on the way forward."

The Scot was also dismissive of Mr Johnson's claim the Brexit dream was dying. "He uses this phrase the dream is over but in the real world, I mean dreaming is good, probably for all of us, but we have to deal with the real world," added Sir Michael.

Meanwhile, Tom Watson, the deputy Labour leader, made fun of the former Foreign Secretary, telling the Today programme: "Look at that guy Boris Johnson, I mean, he's got a career ahead of him on 'Love Yourself Island.’ He's the only politician in history who posed to sign his own resignation letter."

He also suggested Labour backing a new EU referendum was "highly unlikely" but accepted Labour had not taken the option off the table, saying: "It is conceivable that there is no majority position for any deal in the current arrangements in Parliament.

"So, even though we'd prefer a meaningful vote in Parliament, and I have said many, many times it's highly, highly, highly unlikely we will support a people's vote, and we have not called for it, we haven't taken that off the table because there are a rare set of circumstances where Parliament just can't make a decision on it, and in those circumstances you'd keep your options open.”

He added: "'s highly, highly unlikely we'll go down that route."