Peter Kellner: Why Salmond’s three-way choice is less than clear cut

IF ALEX Salmond’s day of destiny were this week, then the outcome would depend on the kind of referendum that was held.

If it were a straight choice, as David Cameron wants, then Scotland would probably stick with things as they are, though a strong SNP campaign might just produce a majority for independence. But if the First Minister won the battle to hold a three-option referendum, then “devo-max” would win.

So why is Mr Salmond so keen on a three-way choice, when it seems certain to kill off any real hope of independence this time round? He is arguably Britain’s most persuasive politician. In a straight-choice referendum held in two years’ time, surely he fancies his chances of lifting support for independence by enough to outpoll supporters of the status quo? Perhaps he’s not so confident of winning a straight-choice referendum after all.

But there is another possibility. He is said to favour not a full three-way referendum, in which voters give their first and second options, but two two-way choices. In vote one, Scots would be asked if they want to move from the present system to devo-max. Then they would be asked if they want to go the whole hog and move from today’s form of devolution to full independence.

Today, Scots would vote “yes” to the first question – but “no” to the second. But suppose Mr Salmond gets his way, not only on the principle of a three-way referendum, but his particular way of asking the questions. And suppose he did increase support for independence during the campaign.

We could then reach the situation in which Scots vote heavily for devo-max (say, 65-35 per cent), and more narrowly for independence (say, 51-49 per cent). What then? Mr Salmond would presumably declare that most Scots had voted for independence. But Mr Salmond’s critics could claim that devo-max is more popular, so Scotland should NOT be granted independence.

In short, if there is to be a three-option referendum, the precise mechanism must be sorted out well in advance, or there could be an almighty bust-up afterwards. One solution is to add a third question to Mr Salmond’s proposal: if there is to be change, do Scots prefer devo-max or independence? This would almost certainly produce a clear majority for devo-max and scupper any chance of Mr Salmond achieving full independence. Could that be why he isn’t proposing it?

• Peter Kellner is president of YouGov. This afternoon he is to give evidence on these issues to the Scottish affairs committee of MPs at Westminster