ALEX SALMOND’S first foray into politics was in primary school, when he represented the Scottish National Party in mock elections—and won, after pledging to replace his fellow pupils’ daily allowance of milk with ice cream. As that party’s leader, he kept the flame burning during the dark days of Tony Blair’s government, when devolution seemed to have killed nationalism stone dead. Given how long Mr Salmond has been pondering the cause of Scottish independence, he might have thought up some better answers to the first real political attack on his plans.

A joint assault from London and Brussels has knocked Mr Salmond onto his heels and jeopardised his chances of winning a referendum, due in September, on Scotland’s future (see article). Britain’s three main political parties flatly declared that they would not countenance a currency union with an independent Scotland. Since four-fifths of Scots want to keep using the pound, this is a devastating blow. Then José Manuel Barroso, president of the European Commission, added that Scotland would find it almost impossible to join the EU.

Mr Salmond has responded with a mixture of bluster, denial, obfuscation and crude threat. How dare Westminster politicians, and especially posh Tories like George Osborne, the chancellor of the exchequer, talk down to Scotland? Don’t they realise it will drive Scots into the secessionist camp? A currency union would work fine, he continues: see pages 140 to 149 of a technocratic review carried out for the Scottish government last year. Any Westminster politician who rules it out is surely bluffing. If by some chance they are not, and refuse to let an independent Scotland share the pound, well, Salmondland will refuse to shoulder its share of the national debt.

This newspaper believes it is entirely up to Scots to decide whether their country should leave the United Kingdom. If they want to be independent, they should go for it. But this week’s fracas ought to give any Scot pause. It has abruptly revealed some of the dangers of going it alone—and some of the dodginess of the man who touts that future.

Mr Salmond promises Scots the grown-up equivalent of free ice cream: an easy separation that will leave everyone better off. This is a confection. An independent Scotland might be able to pay its way at first, but its finances will deteriorate sharply as its people age and the North Sea runs out of oil and gas. Even while it remains a petro-state, Scotland’s revenues will veer up and down with oil prices. It could not sustain its current (very large) welfare bill, let alone the extra toppings the nationalists promise, involving free child care and the like.

Divorce in haste, repent at leisure

And Mr Salmond is wrong: Westminster is not bluffing over the pound. The Treasury means it when it says currency unions only work when budgets are controlled centrally—hardly the autonomy nationalists are planning for. The rest of Britain would also want control over Scotland’s large banks. Sharing the pound might be intolerable even then. Buried in the technocratic report Mr Salmond cites are plans for formal Scottish representation on the Bank of England, but English voters are unlikely to tolerate a foreign country weighing in on their interest rates. Mark Carney, the governor of the Bank of England, delivered the same message as Mr Osborne, more softly.

Nationalists promise, blithely, that everybody will start behaving nicely when Scotland votes for independence. Nonsense: the dispute over the pound is just a taster of the bitter rows that would follow—involving the division of North Sea oil, pension payments and much else. Mr Barroso may overstate the difficulty of Scotland joining the EU, but the process would probably be slow, especially if Britain kicks up a fuss. Mr Salmond seems to forget that British politicians would no longer be beholden to the people of his country.

Picking a fight with Scottish nationalists is a risk, too: it might drive voters into their arms. But Mr Osborne and other unionist politicians are right to do it, because the alternative is worse: Scots voting for independence in the belief that it would come with a couple of scoops and a chocolate flake.