No one saw this coming — and I'm not even talking about the great conservative victory of last Thursday in Britain. I'm just talking about Scotland.

The Scottish independence referendum last September was supposed to have killed off the Scottish National Party (SNP). Once Scots rejected separatism, experts agreed, the separatist party would have no further purpose.

Instead, to the astonishment of pundits and politicians alike, the SNP has pulled off perhaps the greatest electoral achievement in British history. In the last Parliament, the nationalists held six out of Scotland's 59 seats; as I write, they seem to have won 56.

The SNP's breakthrough is a textbook example of what Nassim Taleb calls a "black swan": something that could not have been predicted, and which redefines everyone's assumptions. The commentators who failed to prophesy the SNP surge now lecture us, with Olympian authority, on exactly why it happened. But, in truth, everyone was caught off guard — including the SNP themselves.

The only thing that I can say with confidence is that Scotland has not voted for independence. I say "with confidence" because that issue was settled, on a record turnout, in the referendum seven months ago. The SNP administration in Edinburgh had worded the question in a way designed to boost the "Yes" vote, and extended the franchise to 16- and 17-year-olds, who are disproportionately nationalist. It wasn't enough; and, according to every opinion poll, it still wouldn't be enough. SNP leaders know it. At every election meeting, they insisted that they had no plans to re-run the vote. Sure enough, a fair chunk of their vote came from Scots who said they opposed independence.

So, if Scotland hasn't just voted to leave the United Kingdom, what has it voted for? The answer is depressing. The SNP is best understood as Scotland's version of Greece's Syriza or Spain's Podemos: an anti-austerity party, whose answer to everything is higher spending. Where will the extra money to come from? The party leader, Nicola Sturgeon, tells anyone who will listen that "ending Tory austerity" will of itself boost the incomes of working families, and so generate more tax revenue. Got that? If the government spends more, it gets to spend even more! One wonders, why has no one has thought of this before?

At some point in the past year, political discourse in Scotland cast off the moorings that attached it to reality. Elsewhere, David Cameron was seen as an old-fashioned Tory moderate. In Scotland, he was routinely spoken of as some kind of deranged Bond villain, waging war on the poor for sheer sadistic pleasure. Elsewhere, Ed Miliband was recognized as the most left-wing Labor leader in 30 years. In Scotland, he was a "red Tory," planning deep cuts to benefits. Elsewhere, the BBC was seen as the epitome of political correctness — pro-immigration, anti-Israel, pro-tax, anti-business, yada yada. But SNP activists went on marches against it, because it didn't go far enough for them.

How have these things come to pass in the land that gave us Adam Smith? How can people famed for their frugality, industry and self-reliance have moved so far in two generations? Greece and Spain at least have the excuse that they are being subjected to extraordinary hardship — a consequence of the misconceived euro. But Scotland, like the rest of the UK, has bounced back impressively from the 2009 credit crunch.

So what has gone wrong? In truth, it began in the 1970s, as the shipyards and steel mills closed. A similar process of deindustrialization was unfolding across the developed world, but Scotland was unusual in not having a direct link between taxation, representation and expenditure. Under an odd financial formula, it was automatically entitled to a disproportionate share of UK public spending. Because Scotland was therefore, in effect, spending English taxes, it became completely rational for Scots to vote for high-spending politicians. The public sector became more and more bloated, eventually accounting for 71 per cent of Scottish GDP — a figure that even the USSR never managed.

In such a society, it was hardly surprising that tax-cuts came to be seen as alien and threatening. Nor, indeed, that many enterprising Scots moved to England.

Scotland would today benefit enormously from fiscal autonomy, which is popular on both sides of the border. The Conservative Party, understanding that fiscal autonomy is a prerequisite to its own revival north of the border, is especially supportive of the idea. Yet, despite being notionally committed to more devolution, the SNP is privately reluctant. It fears that an amicable deal with the Conservatives on more autonomy would settle the constitutional question permanently, and put an end to its dream of a separate Scottish seat at the UN.

And so the party aims to keep doing what it has done over the past five years, namely to inflame grievances on both sides of the border — especially to the south. Most English voters are horrified by the idea of being stuck with the bill for a Syriza-type regime and, in my own constituency, I detect a surge in English separatism. England has just voted overwhelmingly for a party committed to tax cuts and deficit reduction; Scotland the reverse. It may well be that the English can be goaded into initiating divorce proceedings.

There's method in what the SNP are doing, I'll give them that. Having failed to turn Scots against the Union, they now aim to turn the English against it. If at first you don't secede ...

Dan Hannan is a British Conservative MEP.