AN independent Scotland would take decades to reorder and stabilise its economy, one of Nicola Sturgeon’s leading advisers on the subject has warned. 

Professor Mark Blyth said the country would “need a 20-year period of getting from A to B”,  and that it would “come with costs”.

He also said leasing the Faslane nuclear base on the Clyde to the UK and US to bring in billions of pounds a year would be better than the SNP’s “knee-jerk unilateralism”, which would “make the economic transition that much harder”. 

The Scots-born academic, professor of international economics at the Watson Institute of Economics at Brown University at Rhode Island, also mocked the SNP’s repeated claim that Scotland would become like Denmark if it was independent.

“No, you wouldn’t be Denmark. Denmark took 600 years to become Denmark,” he said, bemoaning the “complete lack of specificity” in planning for the economic upheaval.

Prof Blyth, who was made a member of the First Minister’s new economic advisory council in July, made the comments days before his appointment was announced in an interview with the Foreign Press Association.

Some of Prof Blyth’s remarks were reported by the Mail on Sunday, but the Herald has seen the full video of the interview in which he makes a series of other points likely to prove uncomfortable for the Scottish Government.

As reported yesterday, Prof Blyth warned independence risked being the equivalent of “Brexit times ten” because of the deeper and longer nature of the Union involved.

He said: “If your argument is that we need to do this because of Brexit, then Scotland separated from England is the biggest Brexit in history. The last time Scotland was fully economically independent, the word capitalism hadn’t been uttered.

“It [the Union] has been together for over 300 years. So, if pulling apart 30 years of economic integration with Europe is going to hurt, 300 is going to hurt a lot.

“That means one of two things. Either you have brass-plate independence — you declare independence, you get a vote, but nothing really changes, you put up some brass plates in Edinburgh, and nothing really changes, you keep the pound and all that stuff.

“Or you go for regulatory divergence — different currency, different economic policy, etc, which will entail significant short to medium-term costs. There’s no way around that. 

“We know that because it’s Brexit times ten.”

The SNP conference later this week is expected to back the removal of Trident within three years of independence.

However Prof Blyth said that ejecting nuclear weapons could deter much-needed foreign direct investment (FDI) from the United States and antagonise Nato and the EU.

He said: “The SNP have embraced a knee-jerk unilateralism, get the nukes out, we don’t want any of that stuff. I don’t know how that’s going to work out in the long-term.

“If the first thing you do is to say to Nato and to the leader of Nato that we’re not going to host any nukes any more, you can forget it, and your submarine access is cut off, you can’t dock in our ports or anything, they’re going to make life very difficult.

“If you do that also from the European side, you’re going to basically bugger up Nato’s only nuclear deterrent, don’t expect them to be too forthcoming on the EU membership.

“On the other hand, if you basically think about this as an asset, one way to do this is to lease the bases. So you would do a joint lease to the United Kingdom and the United States for Coulport, Holy Loch, whatever it is, you declare it ex-ante sovereign territory, you sign a 50-year lease and you get two billion a year.

“You’re doing a transit project. You’re trying to get from where you are economically to where you want to be economically, and basically getting a ton of FDI and getting a transfer of two billion a year into an economy of only 4.5m people, that would be a good thing to do.

“But then, you would have to basically swallow all you’ve said about ‘no nukes’ and all that sort of stuff. So it depends if the politics wins out. If the politics wins out in the way that it’s being written just now, it’s going to make the economic transition that much harder.”

Prof Blyth said he favoured independence on pragmatic and democratic grounds, believing the UK economic model was unstable, while demography meant the population was gradually moving more and more towards Yes.

However he said there appeared to be a lack of economic thinking going on as to how Scotland could move from its current state to a future one outside the UK.

He said there would be challenges, and a new Scottish currency was not a panacea, as it would be pegged to sterling as the UK would still be Scotland’s biggest trading partner.

Discussing the republic of Ireland’s economic struggle after independence last century, he said: “Scotland doesn’t need a 50-year drag but it does need a twenty-year period of getting from A to B, and that’s going to come with costs if it is to be meaningful.

“You can have all the independence you want if at the end of the day nothing really changes - you just change the brass plates in Edinburgh. I think they want more than that. 

“The question is, how do you get from there to there. You need a plan.”

He mocked the SNP’s repeated claim that an independent Scotland could simply be another Denmark, pointing out it borders the massive trading market of Germany. 

He said there was a “complete lack of specificity” in thinking about Scotland’s current business model, and where it wanted to go and how. 

“Instead of which we’ve got, ‘Denmark is awesome. We should be like Denmark. If we were independent, we would be Denmark’.

“No, you wouldn’t be Denmark. Denmark took 600 years to become Denmark.

“How do you become your own thing given where you’re starting? That’s the only thing that really needs to be answered."

He went on: “The Danes have a far bigger connection to Germany [than Scotland]. They’re a peninsular that’s stuck up on the butt of the hinterland of Germany.

“[One view is that] the basic reason that Denmark is rich and cooperative isn’t really it’s social-democratic traditions or any of that, it’s the fact that you’ve got 80m Germans up your backside.”

Prof Blyth’s comments echo those of former SNP MSP Andrew Wilson, who drew up the SNP’s Growth Commission blueprint for independence in 2018.

In recent weeks, Mr Wilson has been urging greater honesty about the transition to independence, given the complication of Brexit that did not exist in 2014.

In response to Prof Blyth’s comment about “Brexit times ten”, a spokesman for Ms Sturgeon said: “Scotland has been torn out of the EU against our democratic will, causing massive harm to our economy and society. Brexit is inflicting huge labour shortages, leading to empty shelves in shops. Independence will give us the chance to rejoin a market around seven times bigger than the UK.”