John Rentoul: It has suddenly become thinkable again that the PM could sack his Chancellor

This week, this column brings you a world exclusive. Secret documents seen by The Independent on Sunday last night reveal that Britain is becoming a more equal country. You may have to read that again. Or perhaps I should rephrase it. The poor are getting richer faster than the rich. That ought to be important news for those who care about social justice, not least because it is the opposite of what nearly everyone believes is the case.

Yet the document containing this information has been on the internet for a week. (Hence my use of the word "secret". There are two ways of keeping things quiet these days. One is to make a speech in the House of Lords. The other is to put an Excel spreadsheet on HM Revenue and Customs website.) It consists of the latest official estimates for the distribution of wealth. It suggests that the richest 1 per cent of the population owned 21 per cent of the nation's wealth in 2003, a reduction from the 24 per cent share the year before. There is also a statistical measure of how unequally wealth is spread throughout the population, called the Gini coefficient (you do not need to know more). It too fell sharply, indicating greater equality, to below the level inherited from the Conservatives in 1997.

However, I might as well be announcing that the visitors from Tharg who rule us through our televisions want us to be purple for all the difference that these sober statistics will make. There is an alliance of left and right that has a vested interest in not allowing populist prejudice (that the rich get richer and the poor poorer) to be clouded by facts. The left believes Britain is becoming more unequal because Tony Blair, the heir to Margaret Thatcher, worships market forces. David Cameron's Conservatives assert the same thing because it makes Blair sound hypocritical and also so they can condemn it, thus proving how compassionate they are.

How inconvenient for both if they had to accept that Britain is - however slowly, like a turning supertanker - moving in the direction of Sweden. We cannot be sure yet that it is, because these are difficult things to measure and we need more data. The figures for the distribution of disposable income, for example, have shown no increase in inequality since 1997. Even so, that in itself is an achievement not to be sneered at, given the global economic forces tending to widen pay differentials.

As it is, the latest wealth figures are also rather inconvenient for the media circus of the past two weeks, which has been rotating around the Blair-Brown tensions. In the circus, the most important news of last week was that the Prime Minister and Chancellor refused to take questions from journalists when they launched Labour's local elections campaign.

Outside the big top, the tentative evidence of greater equality is a huge achievement that belongs to Blair and Brown together. Theirs has been an astonishing relationship in terms of policy, and in what they have achieved for the country together. To think that their squabbling is destructive is therefore to miss the point. On policies to improve work incentives and to lift children and old people out of poverty, the bruising political struggle between them has produced a successful and robust policy mix.

Of course, the struggle is fierce. Brown is desperate to prise Blair out of No 10 as soon as possible. (At this point, though, the Chancellor's supporters in the Labour Party need to pause to consider Cameron's reply, when asked over lunch recently when he wanted Blair to go: "Two o'clock this afternoon would suit me.") Brown knows that time is not on his side - his grip on the succession could hardly be any tighter, so the risks in the passage of time are all against him.

Hence the touches of recklessness. At the local elections campaign launch, Damian McBride, Brown's political adviser, approached Nick Robinson and Tom Bradby, political editors of the BBC and ITV News respectively, in plain view. Minutes later, they both reported that a Brown supporter had told them it was the Prime Minister's people who had banned journalists from asking questions.

What is interesting, though, is what happened next. Blair's entourage, having observed this, discussed retaliating but stayed their hand. As one of them commented, referring to the Prime Minister's relations with his Cabinet: "Even at this stage, TB has got more power than the rest of them put together."

This is raw politics. It has suddenly become thinkable again that Blair might sack Brown, but only if the Chancellor gave him an excuse to do so. He would have to obstruct the Prime Minister on an issue where he was on the wrong side of public opinion. Last week's tactical retreat by the Chancellor on pensions was interesting, therefore. On Tuesday he said he agreed with "90 to 95 per cent" of the Adair Turner report on pensions, which Blair supports rather more wholeheartedly. It was a reluctant bow to brute prime-ministerial power.

All the demands from Brown supporters, noisily amplified by the media, that Blair should "set a date" for his departure are therefore so much sound and fury signifying not so much nothing as weakness. Not least because there is no reason of substance why Blair should. The reasons the Brown people cite are the need for "stability", "order" and "certainty". They sound like shopkeepers in a war zone, rather than policy-makers for the national interest.

Their arguments are undermined by considerations of substance. If the supertanker of economic inequality is indeed being turned round, then this is Brown's achievement as much as Blair's. Nor is there any reason to think that it might be turned round faster under Brown. The significance of the spat over pensions is that Brown takes a more "right-wing" stance - in favour of more means-testing and against higher taxes - than Blair. Not only that, but the previous week the Chancellor ruled out a 50p higher rate of income tax - the left's favourite short cut to greater equality.

What he and Blair have achieved without that short cut (which would have a negligible impact on overall inequality) is a neglected monument to social justice. So the partnership goes on, achieving great things, while supporters of first one, then the other, engage in a vicious faction fight, the aggressors mostly being on the Chancellor's side at the moment. This is because, to the frustration of Brown and his supporters, Blair holds the upper hand, now and for the foreseeable future.