It's Scotland's Oil - no really.

“It’s Scotland’s Oil”, cried the SNP’s infamous slogan from the seventies and eighties. I can still recall a poster depicting a black-caped Margaret Thatcher as a vampire with Scottish oil dripping from her fangs. And to be frank, there were always people, even in the SNP, who thought that the concentration on that single resource was rather tasteless and economically illiterate.

The campaign didn’t chime with mainstream political opinion in Scotland, especially in the Labour Party and trade union movement. These were the days of working class solidarity across borders. Scotland and England were supposed to be working together for the good of all and the maintenance of the welfare state. The idea of snatching all the black stuff for Scotland alone seemed a little selfish. Maybe it was.

But of course Scottish oil was not used to benefit the working classes in the 80s, but to finance the destruction of organised labour and fund tax cuts for the wealthy. There is no doubt that the Thatcher governments depended on oil revenues to pay the cost of mass unemployment. Without the £250 billion that was pumped out between 1975 and 2005, the UK would have been an economic basket case.

This was confirmed two years ago in the secret Scottish Office memo from the economist Gavin McCrone, released under the Freedom of Information Act. “Britain is now counting so heavily on North Sea oil to redress its balance of payments,” he wrote in 1974, “that it is easy to imagine England in dire straits without it” McCrone concluded that oil could reverse the income gap her head between Scotland and England. “For the first time since the Act of Union was passed, it can now be credibly argued that Scotland’s economic advantage lies in its repeal”.

Of course, It may all seem like water - or oil - under the bridge now. Most of the oil has gone. Scotland got some of money back in the form of higher public spending - much of it ironically going on unemployment benefits. But the lack of any tangible legacy has left a bitter taste in Scottish mouths. Scotland is the only country in the world to have discovered oil and not benefited from it directly. The Norwegians prudently ploughed oil revenues into an oil fund which became part of a sovereign wealth fund now worth £350 billion. Norway now bails out Wall St banks.

And it’s not just independent countries that benefit from oil funds. The US state of Alaska has one and so does the province of Alberta in Canada. Even Shetland had direct access to oil wealth from Sullem Voe. Scotland alone remains the ragged trousered philanthropist of petroleum economies.

But times change. Suddenly, with oil at $130 a barrel, the remaining North Sea is valuable again. Scotland will contribute some £14bn in oil revenues in the coming year - £4 bn of that a result of the recent hike in oil prices. John Swinney has written to the Chancellor, Alistair Darling, calling for a proportion of this to be placed in an oil fund to provide security for Scotland in future. He has not had a reply.

The economics of independence are transformed. Only a year ago, Labour was saying confidently that Scotland would be bankrupt if it went alone, not least because oil production had nearly halved from the 1999 peak. However, there is still around 25bn barrels in the North Seat, worth around $2 trillion, and oil companies are exploring previously uneconomic fields. A report by the accountancy firm Grant Thornton last week claimed that an independent Scotland would have a budget surplus of £4.4bn, based on 82.5% of North Sea revenues.

Three decades of neoliberal economics under Tory and Labour governments have eroded any sense that Scotland is morally bound to regard her oil as a common resource. Faced with the unrestrained greed of the City of London, where the people responsible for the credit crisis have just paid themselves £13 billion - almost the equivalent of the entire revenues of North Sea oil- in annual bonuses, it is hard not to argue that Scotland should be getting its snout in the trough.

But a warning. What goes up can go down. While oil may never go back to the days of $25, because of rising demand in the East and the lack of major new discoveries, no one should believe that the current boom will continue. Much of it is the result of speculation, and a correction is more than likely in future. Nevertheless, it has handed the SNP government an extraordinary political windfall just at the moment when it was getting into difficulties over unmet manifesto promises. And it coincides with a growing feeling in Scotland that, this time round, we won’t be fooled again.