Alex Salmond insisted yesterday that he intended to press on with his plans for a referendum on independence for Scotland, to be held in 2010. Self-delusion is, of course, an occupational hazard for those who prefer dream over substance, but this time it sounds as if the leader of the Scottish National Party has lost touch with reality.

Around him, and his party's flagship policy, lies the wreckage of Scotland's independent banking sector, the very symbol of his future hopes for a robust economy. Worse, the two main Scottish banks have been saved from collapse by a Westminster Government, drawing on the resources of the United Kingdom's taxpayers. They are now British, not Scottish banks and their future strategy will be determined from the City of London not Edinburgh.

The twin pillars of Mr Salmond's strategy have long been a healthy financial sector and the price of North Sea oil. With the former in turmoil and the latter hovering around a fragile $80 per barrel, this former banking economist will need more than just his famous bouncy optimism to persuade Scottish voters that now is the time to cast caution to the winds and embark on the brave new venture of independence.

Whether you are one of the 40,000 employees of RBS and HBOS in Scotland, or work for the thousands of companies that rely on the banks' investments, or are part of the sprawling public sector drawing on Scottish bank loans, or enjoy the lucrative sponsorship that keeps the cultural life of the nation afloat, now is the time to consider how you would have fared in an independent Scotland.

Where would that rescue fund,its value estimated at about £100 billion - the equivalent of Scotland's entire GDP - have come from? Would Scotland, as Mr Salmond claims, have had the resources, like Norway, to rescue its own banking system? Or would it, perhaps, have found its exposure more like that of Iceland, a nation facing the prospect of bankruptcy?

It has long been the SNP boast that an independent Scotland, buoyed up by North Sea oil, could become part of an “arc of prosperity”, stretching from Ireland, north through Iceland to Norway, the country which most closely matches the ambitions of the nationalists.

Mr Salmond points to Norway's £200 billion sovereign wealth fund as an example of what Scotland might achieve with the 83 per cent of North Sea oil revenues that he regards as the nation's share. But that fund was carefully built up over 30 years, it is ring-fenced as a pension fund and Norway has only managed to rescue its banks thanks to one of the highest tax and fuel rates in Europe.

What Mr Salmond is reluctant to address is that an independent Scotland would almost certainly have to raise taxes to a level that most Scots would regard as penal, while at the same time pinning its future to the fluctuating price of a barrel of oil. Even then it would be struggling to close the gap between expenditure and revenue. The last published estimates from the Government showed that Scotland spent £10 billion more than it raised in taxes - the equivalent of £1,110 per person. The SNP has always disputed this figure, claiming that North Sea oil revenues would close the gap to £3 billion and, when prices rose above $130 per barrel, the nation would be in surplus.

However, as the global recession bites and oil prices retreat, the argument becomes harder to sustain. At the same time, for those who claim that independence would be a liberating experience for Scotland while introducing the hard-headed realism that stems from raising and spending your own taxes, there is a moral question to address. How does Mr Salmond equate his stance on energy and defence with the harsh realisation that both may depend on the umbilical relationships that make up the United Kingdom?

Defence contracts on the Clyde, naval bases at Faslane, the military infrastructure that sustains jobs and skills - all would be at risk if Scotland broke away. And some day, possibly within the next 20 years, Scotland might find itself dependent on the nuclear energy generated in England which the SNP refuses, at present, to countenance in Scotland. Does the dream of independence survive when the lights go out?

John MacCormick, one of the founders of the Scottish National Party, whose memoirs have recently been published, recalled that the spirit of ambition which drove forward the idea of independence in Scotland had been “crushed by economic disaster” in the 1920s. He believed that, with the growth of postwar prosperity, a new spirit of adventure and ambition had begun to stir in the land.

He might, if he had lived, have accepted that when the harsh winds of recession begin to blow, the Scottish people, a canny lot on the whole, tend to keep their heads down. At such times they are more likely to put their faith in the stability of a tried and tested Union than chance their lot with the empty rhetoric of Mr Salmond.

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