MONETARY policy is economic policy.

Economic policy is always, no matter what they tell you, an arm of political policy. What becomes of a currency and those who use it will sooner or later depend on decisions made by politicians. Sometimes politicians make bad decisions.

You might want some control over all of that. You might settle for just the minimum: a bit of democratic oversight, the occasional chance to throw out a politician whose decisions have done you no favours. But you would not, given the choice, hand over control of the stuff of economic life to strangers whose interests might not be your interests.

The SNP would call that a caricature of the party's strategy for the pound in Scotland's pocket after independence. They would direct you towards the theory of formal – the important word – currency union. Scotland would continue to use sterling after proper negotiations with the Bank of England and the English Treasury. Ground rules would be established. Personally, I don't buy it, not for a moment. I don't buy it along with several other SNP depictions of the promised land. That won't affect my referendum vote, but there is still an argument to be had. The basic question is simple: who says we'll be able to trust the Bank of England?

As I've mentioned before in this space, I once interviewed Eddie George when he was governor of the bank. My trick question was to ask if he could tell me Scotland's inflation rate. Mr George said the data wasn't gathered and indicated that the question was therefore irrelevant. He did accept, though, that there is such a thing as a Scottish economy.

If that was the attitude under devolution, why should anything change when Mark Carney takes over at the bank in June? Rules or no rules, his first responsibility will be to the taxpayers who meet his impressive wages, not to a foreign country. His first duty will be to the distinctive economy of the remaining UK (RUK). That's his job description.

Jim Cuthbert's report for the Jimmy Reid Foundation takes a different tack, but reaches much the same conclusion. He argues, impeccably, that RUK's economic prospects are less than glittering. Rationally, you wouldn't want to bet your future on them. Mr Cuthbert in effect restates one of the better arguments for independence. The UK, as it stands, has little to offer Scotland. The Coalition Government is busy proving the point. As Mr Cuthbert explains it, formalising a currency union with a country afflicted by long-term economic weakness and instability, one prey to poor management and financial speculation, is the last thing we should be contemplating. Besides, you can give such an arrangement any fancy name you like, but independence is not one of them.

Establishing a Scottish currency would not be easy. Speculative markets could well pick on a small country setting out on such an adventure. But wouldn't the same arguments apply to the project the SNP offers when the debate turns to the borrowing and debt management abilities of an independent government?

Isn't oil our guarantee, our letter of credit, the asset that would, to begin with, back a currency as well as it would support Scottish bonds? If Scotland is better placed than most to plan its economic future, as Nationalists always insist, then surely it is well placed to support its own currency.

Unionists make some of these points with their usual glee. They deserve rebuttal. For example, some ask what would become of any currency union if England's Tories get their heart's desire and stage a withdrawal from the Europe Union. It hardly counts as the best case you could make for remaining within the UK, but it contains a fair point.

You can guarantee that in such a circumstance Scotland's needs and wishes would be ignored. You can guarantee, furthermore, that economic policy would become hostage to a Westminster government. Since any attempt to join the euro would amount to political suicide for a Scottish administration – all other arguments aside – an independent currency is the only solution.

What's the purpose, in any case, of a currency union? Nationalists can talk about the interdependence of the Scottish and English economies, the vast amounts of trade at stake, transaction costs, or the overseas territories and Crown dependencies existing happily within the remnant sterling area. None of those is the real justification, even if you do fancy becoming the citizen of a dependency.

The idea, yet again, is to reassure the nervous and the undecided, to give the impression that nothing much will change with independence. For some of us, that's the problem. Nationalist plans have come to resemble a very limited offer. Staying out of the clutches of Nato or the Bank of England are – or were – reasons to vote yes. Proposals to embrace such delights are now becoming reasons to vote against the SNP once independence is secured.

The First Minister says we might have room for a few American bases? That's generous of him. He can guarantee that they will be non-nuclear bases? That's superhuman of him. Someone should read up on New Zealand's experiences in trying to deal with the US as a non-nuclear ally.

The ancient advice to politicians was that they should never confuse a country's currency with patriotism. Policy should not be designed, in other words, for the sake of a status symbol. But if you surrender the currency entirely you have no status as an independent nation. This much is also certain: once locked into a deal with the Bank of England we would never extricate ourselves.

Scotland's economy is at the mercy of George Osborne and a bank that has ventured a trillion pounds to shore up a crooked financial sector. How has the Chancellor been for Scotland, then? And how would Mr Osborne and his appointee at the bank behave if there was a direct conflict between Scottish interests and the interests of the RUK?

The SNP doesn't want to face the question. That's no way to design a programme for an independent country.