Questions, questions...

Of course, Salmond would like Scotland to go for independence direct, but the SNP would be satisfied if the Scots were to opt for a form of federalism, giving Scotland full economic powers but leaving non-nuclear defence, currency and foreign affairs with Westminster. This would be a major step towards independence. So, Salmond wins even if he loses.

Unionists have been slow to understand the significance of this Salmond “double”. Last week they woke up. The UK press has suddenly discovered that devolution max would involve such a radical constitutional upheaval that independence might be an easier option.

Unionist parties in Scotland have sought to under- mine the legitimacy of a multiple-choice referendum. Scottish Liberal Democrats’ leader Willie Rennie claimed the SNP was “rigging” the vote.

The Rennie complaint is this: if you have two separate questions, “independence yes or no” followed by “devo max versus status quo”, who is to say which answer is the right one? What if independence wins in the first ballot by a narrow majority, and devo max wins in the second by a larger majority? Which result takes precedence?

Now, one of the leading experts on referendum law, Dr Matt Qvortrup of Cranfield University, has entered the debate apparently endorsing Rennie’s objection. He indicated last week there might indeed be a problem with a two-question referendum of this sort, because the options might cancel each other out.

Qvortrup advocates the template used by New Zealand’s referendum on electoral reform, where the first question is along the lines of “Do you want to change?”, followed by another question or questions listing the options for that change -- devolution max or independence.

This apparently abstruse distinction caused a row at First Minister’s Questions on Thursday, after which Salmond was forced to make an apology to Parliament for misquoting the Cranfield scholar. The opposition parties said Kevin Pringle, the First Minister’s press spokesman, had tried to “nobble” Qvortrup by putting words into his mouth disguising their disagreement.

Qvortrup insists -- and I have spoken to him -- he “has no disagreement with the SNP leader on this issue”, and he has not been “bullied” or “nobbled” by the First Minister’s spin doctor or anyone else. He says the SNP’s decision to base its referendum on the precedent of the two-question devolution referendum of 1997 is sound.

But, in fact, I fear there is daylight between the First Minister and Dr Qvortrup on this. At the SNP conference last week, Salmond said: “What will be on the ballot paper is a straight yes or no question to independence, that’s what we said we would do in the election campaign.” He went on: “The proposal is to have a second question, in the same way as we had in 1997, which would offer a fiscal autonomy option.”

Qvortrup says he would be happy to advise the SNP on the ballot paper and, if so, I suggest they get together sooner rather than later.

The truth is no referendum is ever perfect, especially when there are multiple options. If you have them all on one paper, and there is an even split between independence, federalism and the status quo, you could find Scotland going independent on the strength of only a third of those who voted for it.

If you use a transferrable vote method, and ask for second choices, similar anomalies can arise. Scotland might end up leaving the UK even though only a minority had this as their first choice.

But the referendum questions do not end there. Professor Vernon Bogdanor, the leading Oxford constitutionalist, argues that, because the issue affects the whole of the UK, the whole of the UK should have a referendum on Scotland’s secession.

And Professor Robert Hazell, of the London-based Constitution Unit, says there should be two referendums, one on the principle of independence and one after the concrete proposals have been debated by Parliament.

Fortunately, Prime Minister David Cameron has made clear that, as far as he is concerned, if Scotland votes for independence in any properly conducted referendum, where the issue is clearly put and the majority sound, then the rest of Britain would have to accept it.

He would regret the disintegration of the UK, but he is not going to send in the tanks. What the PM has not done, however, is say what he would do if Scotland votes for devolution max. Since this is the most likely outcome of the 2014-15 referendum, you might think this is an unfortunate lapse on his part.

All along, the Unionist parties have been assuming the SNP would only raise devo max as a feint, as a distraction from its real objective of independence. But it isn’t quite like that.

The SNP, of course, wants independence as soon as possible, but believes, probably correctly, that if and when a reluctant Westminster tries to respond to Scotland’s demand for devo max, or federalism, its reaction may help propel Scotland towards independence.

English voters have far too much on their minds -- like a referendum on the European Union -- to bother much about Scotland, and they don’t see why they should have federalism or regional devolution forced upon them. Most English people believe they already have a parliament -- called Westminster. The idea of creating a totally new federal system, well, it seems like a long way to go to satisfy the needs of five million Scots.

This might create conditions similar to those that led to the “velvet divorce” of Czechoslovakia in 1992. The Czech Republic decided federation was too difficult and it would be better for Slovakia to become independent, even though Slovakia had not actually voted for separation.

Actually, Slovakia hasn’t looked back; it became one of the fastest growing states in the EU. You could perhaps see Westminster saying to Scotland: look, you’re better on your own -- if you want to work together on things like defence and foreign affairs, come and talk to us. Devolution max? Independence? Same difference.

My own view is the ties that bind the UK would be rather stronger if Scottish independence became a reality. The rest of the UK has not begun to understand the significance of the SNP’s crushing election victory, largely because the UK press focuses on other things.

But one thing seems certain: in this race, the constitutional status quo is an also-ran.