This Budget was a fitting climax to Gordon Brown’s career — or at least what he hopes will be the firsthalf of his career. It will almost certainly be greeted as a success in this morning’s papers; it will probably boost his poll ratings against David Cameron and it will presumably rule out any serious challenge for the Labour leadership when Tony Blair retires.

Mr Brown’s final Budget, appropriately enough, bore all the hallmarks of his long record as Chancellor – and it is this broadly successful record that allowed him to prepare a popular Budget that should provide a good springboard to his Prime Ministerial career. How did he pull this off? Like every Brown Budget, this one relied on three main components: solid economic performance, impressive headline announcements and a degree of sleight of hand in making all the figures add up.

First and foremost is the strong and stable performance from the British economy. Everything else in the Budget — and indeed in Mr Brown’s entire political strategy — depends on the continuation of rapid economic growth and low inflation. If these macroeconomic conditions break down, so will the Treasury’s revenue and spending assumptions. The next Chancellor will then face a fiscal crisis similar to the ones that dogged every British government before 1997.

The fact is, however, that such a macroeconomic breakdown looks very unlikely — and much of the credit for the widespread and probably justified confidence in Britain’s economic outlook must go to Mr Brown. Of course, Mr Brown inherited a good economic legacy from the Tories, but after ten years of carping about the alleged incompetence of Labour economic policies, it is now too late for the Tories to expect any thanks for their contribution to Britain’s economic revival a decade ago.

Yesterday’s warnings from David Cameron, in his Budget response, about the terrible dangers posed by profligate public borrowing, poor productivity and gaping trade imbalances sounded even more foolish than usual, since economic conditions are more likely to improve than deteriorate in the year or two ahead. The figures on Britain’s remarkable economic revival with which Mr Brown began his speech are true. Britain really has risen from last place to second place among the G7 countries in terms of national income per head and we really are expected this year to enjoy the highest growth and lowest, most stable inflation in the G7. If anything, the Budget’s economic assumptions may prove too cautious in estimating that growth will slow from about 3 per cent this year to 2.75 per cent next year and in 2009.

With the US, Europe and Asia all likely to accelerate towards the end of the decade, growth is more likely to surprise on the upside — and while this would not necessarily be good news for everyone, since faster global growth could push up inflation and interest rates, the Treasury’s tax revenues would certainly gain from faster growth, and public borrowing figures would turn out to be a lot lower than the Budget projects.

This strong economic background gave Mr Brown the opportunity he needed to make some impressive headline announcements and he seized it with both hands. The simultaneous cuts in the main rates of income and corporation tax are bound to be popular, even though they will not deliver any large tax reductions to most voters. Mr Brown, to his credit, made it clear from the very outset that he would not be announcing any significant reduction in the total burden of taxes, since he rejected what he described as the Tory “fiscal rule” of continuously reducing public spending. But if he was not really lightening the tax burden, how did he manage, by the time his speech was over, to reduce headline tax rates for both individuals and corporations, while promising vulnerable groups such as low-paid workers, married couples and pensioners that they would all be better off?

Now we come to the third hallmark of every Brown Budget – the element of conjuring. Mr Brown is often accused — and he will be again this morning — of taking away with one hand what he gives with the other. But there is nothing wrong with this. It is what tax simplification is all about. Anyone who calls for a simpler tax code or a lowering of marginal tax rates without any overall reduction in government revenues and spending is calling for exactly what Mr Brown did yesterday. But the problem with Mr Brown is that he can never bring himself to explain publicly the measures he uses to raise funds. It is not as if he is inattentive to detail. He delights in describing all sorts of trivial changes, such as minor VAT exemptions or shifts in the timing of excise payments. But when it comes to the measures that raise large additional revenues Mr Brown’s Budget speeches are usually silent — and this one was true to form. It is not surprising, therefore, that when he finished yesterday the immediate reaction among impartial commentators, as well as opposition politicians, was that his sums did not quite add up.

In fact, the sums do add up — and in quite a simple way. On the personal tax side, the cost of reducing the standard rate of income tax from 23p to 20p is offset by the abolition of the 10p rate band and the increase in the upper earnings limit for national insurance, which will be aligned with the starting rate for the 40p top rate of income tax at £43,000. Between them, these two changes almost exactly balance the reduction from 23p to 20p in the standard rate.

To make sure that lower-paid workers and pensioners do not suffer, Mr Brown throws in an increase in tax credits, which results in a net reduction in total income taxes of about £2 billion a year. If he had explained all this in his Budget, he would still have received and deserved favourable headlines about an important simplification of income tax and a small but significant redistribution of income from the upper middle classes towards people in greatest need. The same would have been true if he had frankly explained his reform of corporation taxes. This, again, was carefully balanced so that removal of various allowances and exemptions would pay for a reduction in the marginal tax rate, which was what the business community demanded.

The question is why Mr Brown could not bring himself to lay all this out quite straightforwardly. Had he done so, he could have rebutted the accusations of stealth taxation that will now confuse his efforts to simplify the tax system and lower marginal rates. More importantly, he might have got some credit for being candid and trying to communicate his message directly to the voters.

This may seem like a minor criticism of presentation, rather than substance. But presentation is going to matter far more when Mr Brown becomes prime minister, as he now almost surely will. He will be leaving the Chancellor’s office with a reputation any of his predecessors would envy. But whether his undoubted success as Chancellor translates into the political reputation he will need in his next office is still an open question.

Times Recommends

• Lies and cover-up at MG Rover exposed by report
• High oil prices push manufacturing costs up
• Primark founder steps down as chief executive