All three parties will be hit by tremors from this earthquake

'The problem is, there is no party currently offering the mob any representation in return for their taxation'

A sign above the television in my hotel room in San Francisco (a city built on the San Andreas fault) gave instructions on what to do in the event of an earthquake: "Take cover and crawl under a table." The warning was an appropriate backdrop as I watched CNN's pictures of Tony Blair doing his daily flip-flops in the Downing Street bunker.

A sign above the television in my hotel room in San Francisco (a city built on the San Andreas fault) gave instructions on what to do in the event of an earthquake: "Take cover and crawl under a table." The warning was an appropriate backdrop as I watched CNN's pictures of Tony Blair doing his daily flip-flops in the Downing Street bunker.

Something of a political tremor, if not yet an earthquake, must have been going on back home when even the San Francisco Chronicle gave banner headline details of "Panic as Britain nearly runs out of gas". Even the Prime Minister, when he finally emerges from the Downing Street debris to face the aftershocks, will surely be forced to acknowledge that yesterday's two opinion polls indicate that something of a seismic shift has been registered on the political Richter scale.

This is, after all, the first time the Tories have led in the polls since Black Wednesday - by coincidence, almost eight years ago to the day. That single event sealed, for ever, the fate of John Major's government, which then drifted, rudderless, to defeat. Was last week the moment when New Labour similarly began to crumble?

Probably not - as long as the economy remains robust. But things will never be "glad confident morning" again, as the panic at the pumps also grips previously loyal New Labour backbenchers in marginal seats. Already Paul Marsden (Shrewsbury and Atcham: majority, 1,670) is first out of the traps with a call for a 10 per cent reduction in the fuel-tax duty. There may be more where he came from.

Much has been made of Mr Blair's attempts to conjure up the ghost of Margaret Thatcher standing firm against the forces of disorder, but a quick examination of the history books shows this interpretation to be rather wide of the mark. In fact, we have been here before, when Mrs Thatcher's chancellor, Geoffrey Howe, tried to impose a similarly massive hike in petrol duty in his 1981 Budget. A peasants' revolt took place on the Tory back benches, and he was forced, under the threat of a Commons defeat, to halve the increase and impose extra tax on tobacco instead. As an MP in a very marginal seat, sitting on a majority of 486 and representing two of the nation's 14 oil refineries, I was inundated with letters from constituents. I took the moral high ground and refused to join the rebels. Andrew Roth, in his parliamentary profiles, records that I called them "rats leaving the sinking ship". At one stroke I managed to upset both the rebels and the Government with my arrogance. But, boy, was I relieved when the rebels won and the Chancellor and I lost.

The crucial difference between 1981 and now lies in the huge Labour majority and, therefore, the inability of the present parliament to act as the nation's safety valve - even if it were sitting.

"No taxation without representation" has been the clarion cry down the ages. The trouble now is that there is no effective representation for those who pay the current petrol impost. All three political parties appear, to varying degrees, to have stopped short of calling for a change of policy. Only when at least one party offers an alternative is it possible to convince demonstrators (who appear to have been acting within the law) that the ballot box is the place to make their protest felt. Hence the frustration; hence the protests; hence the trouble.

The Tories have made only limited political capital out of the issue and are hobbled by the fact that they invented the fuel-duty escalator.

A couple of months ago I noted here that William Hague had made much of fuel-duty increases, and I suggested that his attacks implicitly meant he ought to call for a reduction in petrol tax. I suspect that his hesitancy is due to the same resistance over this issue from his shadow Chancellor, Michael Portillo, as Mr Blair is facing from Mr Brown. Any commitment to a reversal would cause embarrassment for Mr Portillo, whose hands were dipped in oil by the Tory chancellors Norman Lamont and Kenneth Clarke when he served with them at the Treasury during their own massive petrol-duty hikes.

So, Mr Hague craftily made most of his running over Mr Blair's hapless remark that he would have the job sorted out within 24 hours, before tentatively suggesting that a fuel-duty reduction should be "a prime candidate" for consideration.

For Charles Kennedy, the high road of principle beckons, with the call in his new book for fuel-duty increases. In the book, Mr Kennedy condemns the Government for its "timidity" in allowing the hauliers an exemption from the climate-change levy, argues for a road-fuel duty to pay for fleet users to use more fuel-efficient vehicles and advocates a carbon tax, which would get higher gradually.

In Mr Kennedy's words: "Taxing fuel might seem to be an unpopular measure, but it would not have to increase the burden upon individuals because we could use the revenue to reduce tax in other areas."

But his principles got lost when he told David Frost yesterday that he thought road-fuel duty should now be capped. What's more, his environment and Treasury spokesmen are in disarray. While Don Foster says the Government "must avoid cheap, populist fuel-tax cuts", Matthew Taylor says, opaquely, that "the Chancellor must be stone-deaf if he has not heard the strength of feeling on fuel tax". Green or not, they're all over the place.

The nub of the problem is that there is currently no party formally offering the mob any representation, inside Parliament, in return for their taxation. Yesterday's opinion polls show a clear expression of public support for a policy change, which cannot be ignored. Something out there must be stirring among the peasants when Bob Worcester, the head of Mori, says, "Blair hasn't listened. Public opinion is like an 800lb gorilla. He's got it all wrong."

The party conference season may focus minds on the issue. The Lib Dems kick off today, and Mr Kennedy has the opportunity to stand up for fuel-duty rises on environmental grounds.

For Labour, the conference stakes are high. No doubt, ministerial titbits will trip off the rostrum as minor policy announcements are drip-fed to the public in the hope of diverting attention from the petrol crisis and the wretched Dome. Mr Blair will probably take more care not to raise the hackles of Middle Britain with any more nonsense about "the forces of conservatism".

Mr Hague, meanwhile, has been given a slice of opinion-poll luck on which he must capitalise by pressing the Government for a change of policy. He may even now be pondering the consequences of a Scargill-style battle between the Government and the protesters in the run-up to Christmas, which would be unlikely to do the Government's reputation for competence any good. If that proves to be Mr Blair's fate, only worse opinion polls can result, with all that they imply for the outcome of the next election. At that point, Mr Hague will truly seize the initiative if he can then force Mr Blair to delay the election until after next May.

We are now only beginning to realise how politically momentous recent events have been. The after-tremors of this earthquake are not over.

mrbrown@pimlico.freeserve.co.uk