Alistair Darling has opted for one of the latest spring Budgets in modern times, on April 22.

The Chancellor's second Budget will be a month or so later than the usual date, which means that it will be held after the House of Commons returns from its Easter recess.

Officially the reason is that Mr Darling brought forward his Pre-Budget Report (PBR), which contained as many significant tax announcements as any recent full-scale Budget. But the Chancellor is buying himself time to see what happens at the G20 world economic summit in London on April 2 and to see what impact his PBR stimulus is having.

Mr Darling has intimated that he will probably go for a second stimulus in April — in addition to giving help to hard-pressed savers — but he has yet to determine the scale of it.

This Budget will come after the start of the tax year on April 6, but officials say that should pose no problem. The Budget does not in any case become law until the Finance Bill goes through and that always takes several months.

Any tax changes would be backdated through pay packets to the start of April.

It is the latest Budget since 1997. After Labour’s election that year, Gordon Brown delivered a Budget in June to reflect the new Government’s change of priorities.

Many observers believe that Mr Darling will be forced to revise his prediction, made in the Pre-Budget Report in November, that the UK economy would return to growth in the second half of this year. On that occasion, he predicted that the UK economy would contract by between 0.75 per cent and 1.25 per cent, although most analysts now regard that as wildly optimistic.

Mr Darling’s PBR forecast has come increasingly under question by economists who expect the recession to run beyond the middle of this year and possibly carry on into 2010.

In a gloomy quarterly forecast delivered yesterday, the Bank of England Governor, Mervyn King, warned of a "deep recession”.

The Bank made a dramatic downward revision to its growth forecast — predicting that the economy could shrink by as much as 4 per cent in the summer and remain in recession for the bulk of 2009. Mr King said that the prospects for economic growth and inflation remained “unusually uncertain”, suggesting that new types of emergency action would be required soon as cuts to the interest rate — now just 1 per cent — lost their bite.

Mr Darling’s forecasts are more optimistic than those of the International Monetary Fund, which has predicted that the UK economy will contract by 2.8 per cent this year.

The Treasury and No 10 have repeatedly fended off demands for an update on their expectations for the prospects of the economy, by saying that they make economic forecasts only in the Budget and Pre-Budget Report.

The late timing of this year’s Budget will delight many in the City, however. Mr Darling's first Budget last year, on March 12, clashed with the horse racing Cheltenham Festival — an essential annual event for many in the City of London — even though that day’s racing was postponed due to high winds in the Cotswolds.

Mr Darling’s predecessor, Gordon Brown, was always careful to avoid clashing with Cheltenham in his early years as Chancellor, when he was trying to woo the City. His racing-mad press spokesman at the time, Charlie Whelan, ensured that the Budget was held during another week.

This was not the case in later years. There would have been a clash in 2001, when Cheltenham was postponed because of the foot-and-mouth outbreak, and there was also a clash in 2004.

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