We will have to wait until 2018 before a chancellor can again claim to be fiscally prudent. The public finances will not be back in balance until then, even on the Treasury’s own, probably optimistic, assumptions.

By then we will have had at least two general elections, and, if the Conservatives win next year, George Osborne could be delivering his ninth Budget.

The time horizon of Gordon Brown and Alistair Darling is rather shorter: about 13 months before the latest date for the next election. This will, however, include another Pre-Budget Report and spring Budget.

The Labour strategy rests on a combination of getting the bad news out of the way now; hoping, as Mr Darling said, that the economy will “start growing again towards the end of the year”; and delaying the pain until after the election. By his Budget next spring, Mr Darling wants to say that the worst is over, arguing that he has protected you during the recession and will now look after you, and public services, in the upturn.

But even on the Treasury’s forecasts, any recovery in real take-home pay and household spending will be very weak next year, while unemployment will still be rising, and the tax burden will be increasing.

Revealingly, the main praise for the Budget came from the Labour Left, applauding the rise in taxes on the better-off by limiting allowances and bringing forward by a year, to April 2010, the new top-rate income tax band (also increased from an original 45 to 50 per cent).

Many outside groups — including the International Monetary Fund, only an hour after the Budget — say that the Treasury is being too optimistic about a rapid end to the recession, and fast growth from 2011 onwards. If they are correct, the outlook for public finances will be even worse. Mr Brown’s boasts about Labour’s competence and prudence now look threadbare, as David Cameron argued in one of his most effective Commons attacks.

There will be pain for most, not just higher taxes for the wealthy. Duties on alcohol and tobacco are rising in real terms and national insurance contributions will increase next year.

The target for public spending growth has also been revised down again, to only 0.7 per cent a year in real terms from 2011; down from a planned 1.1 per cent last November, and nearly 2 per cent a year ago (compared with growth well above 5 per cent in 2005).

With the debt interest bill due to soar, efficiency savings will not be nearly enough to bridge the gap. So there will be real pain for core programmes. There were few details yesterday. The Tories face very hard choices. The first priority of any new government in a year’s time will be a brutal spending review.

Yesterday’s Budget merely made plain how narrow the options will be for most of the next two Parliaments.

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