As Gordon Brown dithers and slithers in response to blackmail by a few hundred lorry drivers and a handful of panicking Labour backbenchers, it is tempting to conclude that his imminent U-turn on energy taxes is all of a piece with his 10p tax climbdown, his capital gains, inheritance tax and non-dom fiascos and all the other costly blunders since he became Prime Minister.

When he blames the Labour Party's political troubles on the state of the global economy and the fuel protests on Britain's roads on such abstractions as “growing demand and too little supply”, he seems to be turning into his own caricature, especially when goes on to suggest, as he did in The Guardian yesterday, that these problems should be addressed by rearranging the agenda of the meeting of G8 leaders in Japan next month.

Yet lurking beneath the tangled bureaucratic language and the nervous justifications for paying another political ransom, it is just possible to discern the outline of a sensible approach.

While freezing energy taxes would have negligible impact in the face of a doubling in oil prices, a decision to defer taxes for a further brief period could make both political and economic sense - provided it was presented as part of a clear and consistent policy of using the tax system to reduce long-term oil demand. Such a proviso may seem impossible, but imagine what could be achieved if Mr Brown could somehow re-create the strategic, “long-termist” reputation he once enjoyed.

Deferring the increase in petrol and car duties scheduled for October could - and should - be presented as very different from abandoning these taxes. On the contrary, deferral could be presented as a temporary measure responding to the unexpected combination of surging oil prices and slumping consumer demand. The Treasury's quid pro quo for the tax delay this autumn could be a bigger increase in April, designed not only to recoup all the revenues lost through deferral but to raise a lot more. In short, delaying this year's tax hike could be balanced by a cast-iron commitment to restore the so-called “fuel-tax escalator” that Mr Brown foolishly abolished in 1999.

This measure, introduced by Norman Lamont in 1993, committed the Treasury to increasing petrol duties by inflation plus 3 per cent every year. It was one of the best fiscal instruments ever devised by the British Government, since it guaranteed a steadily increasing flow of revenue, which could be used either to pay for public services or for reductions in other taxes. The escalator also improved Britain's fiscal structure by slowly but steadily shifting the burden of taxes from incomes to consumption and from the poor to the better-off.

Finally the fuel-tax escalator had an even greater virtue: it sent the clearest possible long-term signals on energy conservation to drivers and businesses dependent on road transport. Breaking this fiscal cornucopia in his first panic reaction to the 1999-2000 fuel-price protests was arguably the single biggest mistake of Mr Brown's career, forcing him to resort to all the other stealth taxes that ultimately destroyed his reputation.

There was, in fact, only one problem with the old fuel-tax escalator: it was not radical enough. The Treasury designed it primarily to raise revenues in an era before the widespread recognition of global warming, before the rise of Asian energy consumption and before 9/11.

Back in 1993, the imperatives of reducing oil dependence - for economic, environmental and geopolitical reasons - were much less obvious than they are now. As a result, the fuel-tax escalator fell short of what it could have achieved in several respects. It did not raise enough money.

It did not make sufficient allowance for oil-price fluctuations. It was not linked to Britain's international and European commitments. And the long-term signals it sent were not sufficiently clear.

The recent surge in oil prices, combined with the political pressures to defer October's tax rises, now gives Mr Brown and Alistair Darling an opportunity to correct these errors. By doing so they could go a long way to restoring Labour's economic credibility and demonstrating its willingness to govern for the long term. What, then, should the Government do?

First and foremost, Mr Brown should admit that he made a big mistake by abolishing the escalator and announce that under any future Labour government petrol taxes would rise steadily, by the rate of inflation plus at least 5 percentage points. This would give drivers, road hauliers and business transport planners strong incentives to invest in efficient vehicles and gradually to change their lifestyles and business models so as to conserve fuel. And before rural readers barrage me with letters pointing out that driving is unavoidable in the country, let me explain that anyone who is serious about reducing energy consumption and carbon emissions has to create incentives for urban living. Living in the country is expensive from an economic and environmental standpoint - and it is a luxury for which rural populations should expect to bear a cost.

Secondly, having established that energy taxes would rise relentlessly, Mr Brown could give himself some leeway for short-term adjustments of the kind he now requires. He could do this by creating a formula that linked each year's tax escalation to the level of global oil prices. If oil prices rose by more than, say, 50 per cent in a given year, the escalator could be temporarily suspended - but with the crucial proviso that subsequent adjustments would be increased to make up for the revenue shortfall as soon as oil prices began to fall. The purpose of such a formula would not only be to compensate for temporary revenue shortfalls, but also to send a strong signal to energy users about long-term petrol prices.

Essentially, the Government would promise to keep petrol expensive by raising taxes, even if global oil prices collapsed as they did in the mid-1980s. Only if high and rising petrol prices are recognised as a permanent fact of life will drivers and businesses adjust their behaviour.

This leads to the final improvement. Mr Brown is absolutely right to say that energy pricing is a global issue demanding global solutions, but Britain could make a significant contribution by bringing such solutions into being. If Mr Brown were to adopt a tax policy explicitly designed to push domestic petrol prices steadily upwards, regardless of global conditions, he could credibly propose such a policy at the European level as an important step in both environmental and tax co-operation. Given the present anxiety about oil dependence, he would receive a sympathetic hearing from other European leaders.

If the EU were to adopt a policy of steadily escalating petrol prices, the new US Administration would probably follow suit, especially as energy taxes are seen by many American economists as a better weapon than carbon trading in the battle against global warming. In time, even China might adopt similar measures, since it would not want to be left behind technologically, as American, European and Japanese industries and transport systems adapted to the certainty of steadily escalating oil taxes and petrol prices.

So, Mr Brown, put energy prices at the top of the G8 agenda by all means. But instead of just writing articles and making speeches, why not try leading by example?

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