THE craziest thing about this one is the idea that there is a UK single market in the first place.

There is no such entity as the UK single market. The only formal trading bloc to which Scotland is a member, by dint of EU membership, is the EU single market.

Made up of a series of measures and enforced by the European Court of Justice, it exists to eliminate barriers to the free movement of goods, services and labour. And nothing like it exists between UK countries and regions.

All the business that we do now is regulated by those same EU laws, and when we are hoiked out of the EU against our will that’ll all end, putting Scotland on the outside of a market eight times the size of the UK’s.

According to some that’s fine because Scotland does more business with the rest of the UK than the EU. Figures released in January confirm that’s true – exports to elsewhere in the UK were worth £48.9 billion in 2017, up 4.6%.

But it’s bad for Scotland to be dependent on UK trade and that’s why it must diversify like Ireland did. So it’s welcome news that international exports grew at the faster rate of 6.2% to £32.4bn. And sales to the EU were up 13.3% to £14.9bn. The US continued to be Scotland’s top export destination country with an estimated worth of £5.5bn.

We are now on the brink of leaving our fastest growing market. And what happens next remains unclear. It all depends on what sort of deal we leave with, if any – and that won’t be determined by Scotland, but by Westminster.

The fact is, we have no idea what trade is going to look like after Brexit, even at a domestic level.

It is not impossible that the UK Government would seek to establish a formal UK single market in the future, potentially stimulating regulatory competition, but that is certainly not worth banking on.

It’s also possible, as is feared by the Scottish Government, that the UK Government will undertake a “power grab” and claw back competency over devolved matters through a new framework.

But again, we just don’t know now.

What we can say for sure is that the final outcome will be by London-based decision-makers using London-centric thinking.

Last month the UK’s Department for Environment, Food and Rural Affairs said it wants to have “the greatest possible tariff-free and barrier-free trade with our European neighbours and negotiate our own trade agreements” after Brexit, a comment made after a meeting between Scottish seafood industry leaders and then environment secretary Michael Gove.

But after the same meeting, Hamish Macdonell, of the Scottish Salmon Producers Organisation, said officials had failed to protect seafood exports to Europe in a no-deal scenario, stating: “We believe more has to be done.”

If all of this proves anything, it’s that staying inside the UK is a one-way ticket to uncertainty.

In 2014 we were promised that a No vote meant economic safety, business security and regulatory continuity. But, five years on, it is now clear that remaining in the UK does not mean protecting the status quo, because that’s about to be ripped up thanks to the result of a separate referendum in which Scotland emphatically backed Remain, but England voted to Leave.

The only way for Scotland to take real control over trade is to deliver a Yes majority in a second independence referendum – one which would take place against a radically different political backdrop.

It’s worth looking to Ireland for a glimpse at how things could change for an independent Scotland. In 2002, that country sent almost 24% of its exports to the UK and 16% to America.

By 2018 that had flipped, with just 11% sent to the UK and 28.5% entering the US. At around 40%, sales to the rest of the EU were roughly stable.

But here’s the really interesting bit: when Ireland first became independent, it relied heavily on trade with the United Kingdom – to a far greater extent than Scotland does currently.

Now it’s one of the fastest growing countries in all of Europe – and the UK is lagging behind.

That’s what can happen by making independence your business.

WHAT TO SAY

There’s no such thing as the UK single market, and we’re in the process of being removed from a trading bloc eight times larger. The European Union is Scotland’s fastest growing export market and we still don’t know what kind of deal we’ll leave with. Independence within Europe is a safer bet for business.

This article is part of our BUSTED supplement, debunking nine Unionist myths about Scottish independence. It was made possible by support for our 10,000 Steps campaign – if you haven't yet subscribed to The National, click here to find out how it'll help us boost the case for Yes directly.​