What could wipe Salmond’s smile?

Alex Salmond is the canniest politician in the British Isles, a more daunting opponent for David Cameron than Ed Miliband, Labour leader. As London and Edinburgh lock horns over the timing and scope of an independence referendum, the search is on for the Scottish first minister’s weaknesses.

Mr Salmond is smart but not infallible. There are questions about his judgment, an explosive temper is said to lurk beneath his smiling exterior and he can be over-confident. He overstepped the mark on Friday, for example, by likening London’s “bullying” of Scotland to Britain’s historically violent treatment of Ireland. Mr Cameron has as yet ordered no executions.

In the first Holyrood election in 1999, Mr Salmond made two errors: attacking Tony Blair’s and Nato’s military intervention in Kosovo as “unpardonable folly”; and his “Scotland’s penny” campaign, which assumed Scots would pay 1p more on income tax than the rest of the UK to fund better services. It backfired, the Scottish National party lost and Mr Salmond quit as leader 18 months later.

Returning in 2005, it was a mellower Mr Salmond who rebuilt his party on the centre ground and beat Labour by a single seat in 2007, offering a council-tax freeze and investment in policing and schools. But the financial crisis raised the judgment issue again, after his enthusiastic support for Royal Bank of Scotland’s disastrous takeover of ABN Amro and his championing of an “arc of prosperity” including Ireland and Iceland.

That positivity, however, is a crucial reason for his success: he gives a relentlessly optimistic view of Scotland’s future and has suppressed the SNP’s traditional air of anti-Englishness. Helped by weak opposition, he won a near-impossible overall majority last year. Even freeing Abdel Basset al-Megrahi, the biggest mass murderer in Scottish history, did not set him back.

Despite his aura of invincibility, Mr Salmond has a hard task to achieve independence, even if he muddies the waters by asking an additional “devolution max” question. But if he fails, it may be because of errors he makes rather than the ability of London politicians to outwit him.

Yes, no, maybe

Some argue that, since there is more than one party to the union, the rest of the UK should also vote on Scottish independence. While there may be a moral case for that, the political consequences make it hard to countenance. Even leaving aside whether the complex “devo-max” option should be put, a simple vote on independence could present difficulties.

If Scotland voted Yes to independence and the rest of the UK No, the result would be simple: Scotland would leave. But if Scotland voted No and the rest voted Yes, think of the outcome: a large country would be, in effect, expelling a component part of itself that did not want to go. I struggle to think of any international parallel.

An even more frustrating outcome is possible. Imagine if Scotland voted No and England voted Yes, but Wales and Northern Ireland voted No by enough votes to overcome England’s Yes. All would then be locked in a loveless union, knowing the English wanted rid of the Scots.

Price tag: £500

Last year the ScotCen Scottish Social Attitudes survey found that, while only one in three backed independence, this would rise to 65 per cent if people believed it would make them £500 a year better off. But if they thought it would leave them £500 a year worse off, only 21 per cent would support independence.

Hard-headed good sense or a stereotypical Scots attitude to cash? It suggests that, 305 years after a union derided by Robert Burns as a sell-out by a “parcel of rogues” who were “bought and sold for English gold”, personal financial calculations will play a crucial role.

Back to the bawbee

Would an independent Scotland have the pound sterling or the euro as its currency, or something else altogether? The old “pound Scots” would be the most obvious, similar to the Irish punt. Any number of pre-1707 names for Scots coins are available, such as the unicorn (gold, 18s Scots), merk (silver, 13s 4d), groat (silver, 8d), bawbee (copper, 6d) or bodle (copper, half-groat).