Speaking to the Scotsman, the Prime Minister said the government would hold the “widest possible consultation” with devolved administrations ahead of the next phase of negotiations on future trade with the EU, if he secures a majority and delivers his Brexit deal.

Mr Johnson said he understood the feelings of a growing number of Scots willing to consider independence as an alternative to leaving the EU.

But asked if he would ever approve the powers under the Scotland Act to hold indyref2, the Prime Minister said: “I’m ruling it out. I think it’s a bad idea.”

In an interview with the Scotsman, PM denies blocking second referendum after 2021 SNP win would be undemocratic. Picture: PA

Mr Johnson highlighted new Royal Navy shipbuilding programmes to build Type 26 frigates in Govan and the just-announced contract to assembly Type 31 frigates in Rosyth, as well as the COP 26 international climate change conference due to take place in Glasgow in a year’s time as signs of the UK government’s growing commitment to invest in Scotland.

“Look at the nine or ten billion in extra spending that goes to Scotland as a result of membership of the Union,” Mr Johnson said. “Seriously, it really grieves me to think that this could be pulled apart. And I don’t think it should be.”

The Prime Minister said: “I’ve made it very clear that the people of Scotland were told emphatically in 2014 that this was a once in a generation event, and they were promised that they would not be driven to the polls. I think we should we should abide by that.”

He added: “I understand people’s feelings and I respect those feelings. Totally, of course I do. But the promise in 2014 was very important. Nicola Sturgeon made it too.”

Mr Johnson rejected the suggestion that denying a request to hold a second independence referendum if the SNP won a majority in the 2021 Scottish Parliament election would be undemocratic.

Instead, when asked how he would heal the country and bring the Scottish public together despite deep divides over Brexit and independence, Mr Johnson said: “When people voted to remain in 2014, they should feel that that democratic view is going to be honoured for as long as they were told it was going to be. Similarly, when people voted to leave the EU in 2016, I think that democracy should be observed... I think that people on both sides of the argument do get that.”

The Prime Minister added: “I think we do need our national debate to become less acrimonious... I think that feelings have been running high I think that the best way forward is to get Brexit done.”

He repeated warnings of a “chaotic coalition” between Jeremy Corbyn and Nicola Sturgeon, saying a Labour administration propped up by the SNP would be “ruinous” for the UK and its economy.

Attacking Mr Corbyn over the confusion surrounding Labour’s stance on allowing a second independence referendum, the Prime Minister added: “The putative future Prime Minister… we don’t even know what his position would be on either referendum. You know my position.”

Mr Johnson was filmed on a recent visit to Northern Ireland telling business leaders that the region had secured a “great deal” through his Brexit renegotiation with Brussels because “you keep free movement, you keep access to the single market” - two key demands made by the Scottish Government and rejected by successive administrations in London.

“No part of the UK is staying in the single market,” the Prime Minister said when challenged over the comments. “Let’s be absolutely clear about that. There will be a very, very clear distinction between all parts of the UK and the EU in the sense that EU law ceases to operate.”

He added that the Scottish Government’s call for devolved immigration powers “would involve a hard border at Berwick”.

With 2020 set to be dominated by political wrangling over trade talks with the EU even if the Tories win a majority, Mr Johnson said it was “too early to say” what role devolved administrations would have in his negotiating team.

“I will want to make sure that we have the widest possible consultation,” the Prime Minister said.

No second independence referendum as long as I’m PM, Boris Johnson tells Scotland