With less than a week before his inaugural budget, Alistair Darling is being pummelled with advice from economists and accountants as his civil servants scrabble around in the public purse for pennies. But the professional number-crunchers are useless; he is a man in need of an escapologist, not an economist.

The Chancellor is mired in a fiscal hole dug by his predecessor. After ten years of immoderate spending, the public finances are in utter disarray. Mr Darling badly needs to plug the gap by raising taxes or cutting spending, but, with an economic slowdown looming, the prudent move could also be highly imprudent. Putting the squeeze on consumers or business now could dampen growth just as it needs stimulating.

Some pundits believe that the Chancellor would be better to sit tight, do nothing and let borrowing take the strain. Yet Mr Darling has already been forced to raise his borrowing forecast for 2007-08 to £38 billion. If a slowdown hits tax revenue, the Government's borrowing forecasts for the next few years will look as if they were formulated by the chief economist of Oz. So Mr Darling can raise taxes, annoying the voters and flattening growth, or he can push Britain even further into the red. Neither of these options is palatable.

Nevertheless, on Wednesday Mr Darling will have to attempt to scale the sides of the hole. He cannot count on a handy rope ladder from Mervyn King. The Bank of England, concerned about the growing threat of inflation, is not expected to cut rates today. Any stimulation for the faltering economy will have to come from fiscal policy, not from the rate-setters.

Sitting down there in his dark fiscal hole, Mr Darling may reflect bitterly on years in the sunny uplands enjoyed by his predecessor. Gordon Brown spent his way out of the economic downturn at the turn of the century and then carried on spending through the boom years. Mr Brown preached prudence and accumulated debt. Will the present Chancellor have the cheek to hypocritically lecture voters on their savings habits or to talk of prudence?

There is one route out of the hole, which would save face if not the nation's finances - the rope ladder could be made of green taxes. Among the front-runners for revenue-raising green tricks expected in the Budget are taxes on plastic bags and a new levy on aircraft passengers.

If Wednesday's Budget is a green one, do not be fooled by the rhetoric. The measures will have little to do with saving the planet and everything to do with Mr Darling's dilemma. This Budget is being written to save only one endangered species, and it answers to the name Darling.

antonia.senior@thetimes.co.uk

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