What we’re actually discussing isn’t whether the rest of the UK would accept a currency union in principle, but what they’d ask in return. For it to be in Scotland’s interest we’d need the Bank of England to act as a lender of last resort (otherwise we’d be open to bond market speculation and might have to pay a far higher rate of interest on our debt). The rest of the UK might also insist on a fiscal compact. They might insist on a budget scrutiny mechanism, and there would be negotiations over how much of the national debt Scotland takes on.

These are all serious issues that can transform a currency union from being the simple no-brainer the SNP are portraying it as, to something that isn’t actually in Scotland’s interest at all. So while it might be mutually beneficial to have a currency union in principle, that doesn’t really get us very far if we don’t know what the substance of the agreement would be. If I walk into Tesco and say it’s mutually beneficial for me to buy my groceries from them then I’d be completely correct, but that doesn’t mean I can dictate the price I pay at the checkout.

On the currency issue, for example, we know that abolition of the currency union will cause serious problems for the rUK. We know that Scotland is rUK second largest trading partner and so it would be very much in the interests of the rUK to keep business transaction costs low and cross-border trade simple.

We know too that abolishing the currency union would add circa £50 billion to rUK’s trade gap. It is rather obviously in rUK’s interest to avoid that.

So it is not a case of the Scottish Government defining rUK’s interests but very much one of acknowledging the reality. Something the anti-independence campaign is very reluctant to do.