But this time it feels different. It is true that all the attitudes that characterised previous surges in the oil price are evident now. There is the resentment against the oil companies at their profits. There is the cockiness of Opec, with its president warning on Monday that the price might go to $200 a barrel. And there are the exhortations to conservation, but without much follow-up.

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Here's why. It is that the balance of power between those two old warriors, supply and demand, has irrevocably shifted.

Supply, as Opec keeps reminding us, is tight. Any disruption in supplies has therefore a disproportionate impact on the price. You can see that in the way disruption in the North Sea and Nigeria pushed up the global price over the weekend. Some 60 per cent of the world's supply comes from the non-Opec producers and they are pumping at or close to their limits.

You could say, over-simplifying grossly, that this "Nopec" oil is difficult-to-produce oil in politically easy places, whereas Opec oil is easy-to-produce oil in politically difficult places. As far as Nopec is concerned, many of the easier (ie, cheaper to produce) fields, such as on-shore US supplies, are in decline. The first generation of off-shore fields, including the North Sea, are in decline too.

Oil is still being found but the really big opportunities are in non-conventional sources, such as shale oil and tar sands, and these are expensive to exploit and may carry high environmental costs. So, over the next generation, the total Nopec supplies may creep up a bit – though even that is not clear – but it is not going to be cheap oil.