With pleasing arithmetical symmetry, the £32 billion given to HBOS and RBS is just about the total current budget of the Scottish Government. With HBOS set to take £20 billion of taxpayers' money, the £100 million that Alex Salmond, the First Minister of Scotland, offered to forestall the merger with TSB suddenly looks rather paltry. The credit crunch has already claimed some significant victims. The credibility of Scottish independence is next.

The case for independence has always rested on the claim that a low-tax, business-friendly economy, no longer shackled to its dominant neighbour to the south, was more than capable of prosperity alone. The bounty of North Sea oil reserves would be returned to their rightful domicile, more than offsetting the depletion of funds from the loss of the generous political settlement of the Union with Great Britain. The international chambers of the world would reserve a seat. With full EU membership assumed, Scotland would flourish like Ireland or Norway or Iceland, the once-upon-a-time “arc of prosperity” to which the First Minister regularly pointed.

Suddenly, every part of that case looks flimsy. The small nations no longer look quite so exemplary. Ireland has gone into recession; Norway has gone cap in hand to the US Federal Reserve for a $5 billion (£2.9 billion) lifeline; Iceland has gone fishing.

The foundations of the economic case for independence were always insecure: some heroic assumptions about tax revenues, a massive bet on the oil price and a fond hope that Scotland would get by on North Sea oil reserves. If independence now looks like a chimera that is because it has been exposed as perhaps too great a burden.

If Scotland were an independent nation today it would have been negotiating a rescue package with a foreign central bank and asking a foreign government to secure its deposits. And the Scottish National Party (SNP) policy to have no central bank looks especially foolish in a context in which procrastination by the Bank of England has exacerbated the crisis of liquidity.

When the Scottish financial sector, the fifth largest in Europe, cannot survive without help from London, the case for the Union is strengthened. It has not only been foes of nationalism who have pointed out that it helps to be part of a greater entity when a crisis ensues. It is difficult to argue that the Union is a shackle when, in a strange echo of the generous Barnett formula, a great deal of taxpayers' money is heading from South to North to rebuild the balance sheets of Scottish banks.

For someone who is himself a former economist at RBS and usually a politician fleet-of-foot, the First Minister has had a poor financial crisis. The chair of his Council of Economic Advisers, Sir George Mathewson, himself a former chairman of RBS, has also been eloquently silent about how an independent Scotland might have coped. The First Minister is, of course, playing a very long game indeed. He has a strategy of inevitable gradualness in which independence is secured in 2017 after a spell of sound SNP government and a Scotland-denying period of Unionist Conservative rule from London.

The first test will come at the Glenrothes by-election where a SNP victory is prematurely already in the price and where a revivified Prime Minister will hope for his reward. A referendum is in the calendar for St Andrew's Day 2010. Whenever the Scottish people have been polled, they have consistently upheld the Union.

The financial crisis of 2008 may be attesting to their wisdom. The Union that has served them for three centuries may be the only asset in Scotland that has not depreciated sharply over the past two weeks.