The Chancellor has survived this test, but the future looks rather less rosy

Mr Brown's presentation at the Dispatch Box yesterday expressed not a scintilla of doubt, self-directed or otherwise

There are times, in retrospect, when the first Blair term looks like a dress rehearsal for real politics. There were big moments of course, the Belfast agreement and Kosovo foremost among them, just as Iraq looms now, its high moment of danger perhaps no more than weeks away. But on the home front, the crises, spats and wobbles of that era now seem lilliputian in comparison with the tests ahead. Those, illuminating as they were, were about the process rather than the substance of politics: spin, overzealous fundraising from business, control freakery, an approach to the press at times informed by shameless populism.

It's very different now. The post-spin age beckons, not only because spin became counterproductive but because it seems irrelevant to the scale of what the Government has to contend with between now and the next general election. Neither the customarily impressive array of initiatives for enterprise, for pensioners or for world poverty announced by Gordon Brown yesterday, nor the chronic electoral weakness of the Opposition, can disguise the fact that the gears of real political economy are now fully engaged.

Dangers either loom or are already present, among them a firefighters' strike, which the Chancellor yesterday rightly reminded MPs, as forcibly as he has yet done, that the Government cannot afford to lose. The no doubt fraught debate, first and foremost between the Chancellor and the Prime Minister, on whether Britain should enter the euro is real and, at long last, inescapable. And most real of all is the question, linked to both the first two, of whether the Government's economic record, unmatched by any previous Labour administration, can be sustained.

On the last and most electorally fundamental of these questions, Mr Brown's presentation yesterday exposed not a scintilla of doubt, self-directed or otherwise. Anybody who expected him to come to the dispatch box yesterday in a mood of humility about his downward revision of the growth forecast and his upward revision of borrowing plans, misunderstands not just the man but perhaps the nature of modern politics.

While it is a given that every politician of the front rank in every government blames world factors for the bad news and takes exclusive credit for the good, Mr Brown was certainly at his most persuasive in attributing a revision of the forecasts – a revision that he did not explicitly mention, preferring instead simply to announce the new figures as though there was nothing out of the ordinary – to a stagnant global economy. In doing so he appeared to dismiss suggestions made at the time, not least by his predecessor Ken Clarke, that these were on the heroic side.

Even more striking to the layman was his insistence that the Government's tax and spending plans, now augmented by a further £1bn if needed for the so-called war against terrorism, would be maintained intact. And that the cycle would right itself in time for the borrowing level to meet the golden rule that the Chancellor set himself from the moment of taking office.

That, too, is probably a necessity of politics, and not just the modern version. The Government, having taken its momentous, defining step in the last Budget to raise taxation for the public services, could hardly have performed a U-turn by announcing after all that this would be impossible and that either taxes might in the medium term have to be raised further or spending cut. If it had done so, a great deal more than the Chancellor's reputation would have been at risk. Moreover, having been a lucky as well as an outstandingly skilful Chancellor, Mr Brown could yet prove triumphantly correct in the belief that radiated through his bullish speech yesterday that his luck was not about to run out.

That said, he has left himself very little room for manoeuvre if it does. There was not even a subliminal hint to the backbenchers behind him that further difficulties and further revisions could not be ruled out for the future. As Hamish McRae pointed out here yesterday, not only were the tax and spending plans in the Budget based on the previous forecasts, but income tax is below projections and public spending has risen more than expected. Mr Brown was equally persuasive yesterday in arguing that the Government's ability to borrow was underpinned by its historic success in having reduced debt from 44 per cent of gross domestic product to 36 per cent. But facing factors he cannot altogether predict or control, Mr Brown cannot yet be as certain as he sounded yesterday of wholly escaping the long shadow cast by another brilliant Chancellor, Nigel Lawson, whose career still ran up against the very boom and bust his Labour successor has staked his reputation on eradicating.

Both he and the Government, however, are helped by an Opposition ill-equipped to capitalise on these uncertainties. Within the constraints, Michael Howard, who isn't as frightened of Mr Brown as his predecessors, did well yesterday, particularly in drawing attention to the off-balance-sheet commitments for public projects undertaken by private industry. But the present Tory regime remains inhibited by its identity crisis on overall tax and spending from exposing itself to the argument that it would decimate public services. It's an oddity that the Tory left, as represented by Kenneth Clarke, is in a better position than the right to oppose the Government on economic policy precisely because it is less likely to inflame such fears of unacceptable state shrinking when it calls, as Mr Clarke by implication did yesterday, for fresh curbs on tax and spending.

What's more, it's a mistake to see problems, however serious, as a crisis. It's unlikely that Mr Brown's Budget in the spring will see a reverse of the Government's overall strategy any more than did his statement yesterday. The big event of that period is much more likely to be turbulence as the Cabinet decides on euro-entry. While remaining impeccably within agreed policy, Mr Brown's body language continued to suggest yesterday that he still thinks the British currency and a British central bank are best placed to see the country through the troubles ahead.

But there will certainly be competition between that argument and the one aired below by Sir Michael Heseltine, that economic difficulties are better faced within the eurozone than without. Either way, it could yet provoke fissures along the lines of Lawson-Thatcher – with the difference that Mr Brown wants Mr Blair's job and Lord Lawson didn't want hers. Another key factor here could be how the Bank of England's new governor, Mervyn King, sceptical but also a pragmatist, decides to jump.

Meanwhile, Labour MPs will be fervently hoping that Mr Brown's impressively robust presentation yesterday is justified by events. It may yet be. But if not, the prospect remains that the next Comprehensive Spending Review, shortly before a 2005 election, could mark some unwelcome belt-tightening. Yes, politics is real again.

d.macintyre@independent.co.uk