The SNP wants Scotland to leave the UK, to separate from England, Wales and Northern Ireland. Why? What is it we are supposed to want that we don’t have or want to get rid of that we do have? What exactly is the detailed prospectus we – citizens and businesses – are supposed to read and want to buy?

We had such a document before the once-in-a-generation independence referendum.

The SNP Government produced “Scotland’s Future”, a vision where life got better for Scotland, its businesses and its people based on assertion, hope and a sea of oil.

Looking back it was a load of rubbish, a fantasy, a recipe for heartbreak and disappointment. Fortunately, the Scottish electorate did not fall for it in 2014.

The SNP tried once again to sketch out for us their vision of an economic future – the 2018 Growth Commission report.

This was an attempt at realism – but it was again actually far too optimistic because it assumed growth rates and currency outcomes which were – and still are – undeliverable.

This report, which dared to suggest some restraint in public spending, now looks like the document before it – a naïve fantasy.

Yet the bulk of the SNP rejected it because it was too financially responsible – not enough public spending.

The SNP is smarter now. It doesn’t set out a detailed vision, it just assures us all would be better if we were on our own and complains and moans and picks fights with any person or institution it sees as British.

So, if the SNP won’t tell us, we have to work it out ourselves.

Can a separate Scotland keep the pound sterling as its own real currency? No it can’t. Can it re-join the EU? After we have tackled our fiscal deficit probably we could but we would have less influence on the EU than we have in the UK and we would in time need to take the euro. Can a separate Scotland continue to be part of the single UK market which is vital to our economy? No, if we join the EU we cannot.

Could we afford to spend more money on schools and hospitals as a separate nation? No, we would have to spend less because the fiscal transfers from the rest of the UK would cease. Could we borrow more money to make up the difference ? No, with our budget and trade deficits we could not borrow except at penal rates. In any event our wish to rejoin the EU means we must borrow much less, not more.

So what is it we do want? Our own Navy or DVLA – doesn’t seem like a good plan when we share excellent ones already. Is it to be able to run our own hospitals and schools? We already do that.

Is it to decide how we deal with a pandemic? We already are. Is it to set our own taxes? Well in most cases where it makes sense to do so we already do.

In terms of the things which touch people’s everyday lives, Scotland already has a large degree of independence.

Are there other powers which could sensibly be devolved to Scotland? Yes, of course there are but our Government is so intent on falling out with the UK Government and creating division and antagonism that it can’t have a sensible dialogue to enable that to happen.

To separate Scotland from the UK, whether or not we then rejoined the EU, would be an act of extraordinary economic folly – far greater than Brexit. Scotland gains from being part of the UK.

There is no credible prospectus for a more successful prosperous Scotland outside the UK. A Scottish Government which really wished to serve the people of Scotland would have the honesty to face reality and work with the other nations of the UK to build a better future together.

Guy Stenhouse is a Scottish financial sector veteran who wrote formerly as Pinstripe