Nothing will bind Tony and Gordon closer than the pickle they're in

It is like I'm A Celebrity. You know it's there, because you read about it in the newspapers all the time. But have you ever seen it? Does it really exist? What is the evidence that there are people in a real jungle in Australia?

It is like I'm A Celebrity. You know it's there, because you read about it in the newspapers all the time. But have you ever seen it? Does it really exist? What is the evidence that there are people in a real jungle in Australia?

It is the same with the great Brown-Blair feud. It is an epic opera of towering emotions, about which we read all the time. We know it is there, yet it is never seen in public. When the Chancellor rises in the House of Commons on Thursday to give his pre-Budget report, he will not mention it. But everyone listening knows about it and will be looking for clues as to how the hidden plot is unfolding.

This will be Gordon Brown's first big parliamentary occasion since the Prime Minister said, yes, he had bought a house in preparation for moving out of Downing Street, but, no, he wasn't going yet. That coup suppressed speculation about the Brown-Blair struggle for a while, but last week it bubbled back up. Peter Mandelson, European Commissioner for Trade, repeated his support for Britain's early adoption of the euro. Was it reported as a contribution to an important debate about the nation's future in Europe? No, it was an "attack on Brown". Denis MacShane, the Europe minister, said that Britain must respect the interests of other member states. That was a "coded criticism" of Brown. Meanwhile The Sun repeated common Westminster speculation that Blair might try to move Brown from the Treasury after the election. Yesterday, Trevor Kavanagh, The Sun's political editor, reported that Blair threatened to sack Brown last year if he did not help to join the euro. Because Kavanagh enjoys good access, it is often assumed that his information comes from the Prime Minister.

It may do. But the best guess is that Mandelson and MacShane were not deliberately trying to get at Brown, and that the Prime Minister did not plant a report in The Sun as a warning to his Chancellor. The trouble with all this stuff is that we do not really know. And there is enough in the public record that is unambiguous evidence of the tension between the two powers of the Government. Alan Milburn's return to the Cabinet was an appointment of stunning brutality, an assertion by Blair of his control over the election campaign. Brown's response to that provocation has been muted. He made a rather mild defence of "the ethic of public service" in his speech to Labour conference, saying it was a value "far beyond" that of "contracts, markets and exchange". That is unmistakeably different from the Prime Minister's view, but not irreconcilable, and it has few practical consequences in the short run.

And that is the problem with the Brown-Blair story. It is remarkably difficult to point to ways in which it has affected anything outside the city of words constructed by journalists. Even Peter Hennessy, the chronicler without compare of the British premiership, has returned baffled from his forays into the deepest recesses of Whitehall. In a recent lecture, he rightly observes that the familiar picture of a "Blair presidency" is inaccurate, and that it is "more of a dual monarchy of a very peculiar kind". He comments: "What you really need is a medievalist not a contemporary historian to depict it."

It is a dual monarchy that has never allowed an open breach on policy. Not even on the most contentious issues, namely the euro and decisions over taxes and spending. Brown has prevented Blair from preparing to join the euro, but does anyone think a referendum would have been winnable at any time in the past seven years just because Brown as well as Blair was making the case for it? Blair pre-empted Brown's spending plans by announcing from David Frost's sofa that he would match European levels of spending on the health service (a pledge that has fallen behind schedule, but hardly anyone has noticed). But the increase in public spending was a joint strategy and Brown was irritated because he wanted to take the credit for it.

Brown came close to destroying the plan for higher student tuition fees, but the critical thing is that, when it came to the point of decision, he did not. As Professor Hennessy points out, if Brown had insisted that an explicit resolution of the United Nations was required to justify the invasion of Iraq, then British troops would not have taken part. But, when it came to the point of decision, he did not.

Some of Brown's supporters among Labour MPs have lost patience with him. "He has missed his chance," one of them says. He could have brought Blair down, but he refused to. Now he will not get another chance for two or three years, and who knows who else will have emerged as a possible successor by then? He might as well go and be head of the IMF.

That, I think, is a misreading of Brown's position. First, because he could not have been remotely sure of bringing Blair down. Second, because Brown and Blair understand, in a way that some of their supporters do not, the nature of their dual monarchy. They are bound to each other by a common interest. They do not have to like each other or even trust each other. "Like" is not a word politicians use much, and Blair is not exerting himself to ensure Brown's succession. Not out of spite, although that may come into it, but because it is not in his interest to have an heir too apparent, and Brown is already dominant enough among the dauphins. Brown, on the other hand, knows his best chance lies in giving Blair the space to step down with dignity.

Which brings us back to this week's pre-Budget report. The Chancellor is not in a strong position to use it to set out an alternative manifesto. For one thing, he has no money to pay for pre-election surprises. The public finances are in a poor state. You do not need to remember what the golden rule is to know that the Government should not be borrowing large sums of money while the economy is growing strongly. Labour cannot, therefore, go on increasing public spending at the present rate for much longer. The formula for public services, more money plus reform, will soon have to switch to just reform. But Blair and Brown are in that pickle together. Brown enjoyed being held solely responsible for steady economic growth, but you can be sure he and Blair will share the blame if the public finances go wrong.

New Labour has certainly learned the lesson of George Bush's election victory, but not the lesson everyone thinks it learned. The lesson was not that frightening the voters with the spectre of terrorism pays dividends for incumbent governments. It was that reckless public borrowing is not something that voters worry about, at least not until they have to pick up the pieces several years later. The pre-Budget report may be fiscally irresponsible, but Brown and Blair are being irresponsible together, and nothing will come between them until the general election is safely out of the way.