Steve Richards: The question is not when Blair will go, but the kind of Labour Party Brown will inherit

The metaphor of the clock being turned back risks framing Labour's internal debate in fatal terms

Head for cover. A volcano of news stories, articles and columns is heading your way on the future of Tony Blair and who will succeed him. The volcanic tremors will be loud and long lasting.

Yet the questions relating to the precise timing of Mr Blair's departure and about who will take over are tiny. We know the answer to one and almost know the answer to the other. The pivotal issue for Labour over the next few months is the context in which the new leader takes over. This matters much more than whether Mr Blair leaves this autumn or next year, or whether another deluded cabinet minister believes that he could seize the crown.

Indeed the seething speculation gives the false impression that the new political season opens in a deep fog, where nothing is known. The opposite is the case. The really big story is how much we know about the future, not how little. Imagine if Mr Blair had not pre-announced his departure. The Labour Party would be in a much greater state of fuming insurrection with wholly unpredictable consequences. Far from being a mistake, it is only Mr Blair's cunningly multi-layered pre-announcement, in which he said he would not serve a fourth term, that gives him a small amount of breathing space now. The declaration was an act of genius, somehow made more artful by the fact that Mr Blair contrives to regret making the commitment now.

Such is the anger within the Labour Party about Mr Blair's foreign policy and parts of his domestic agenda that he would probably be facing a leadership contest this autumn, one that he would have lost, if his departure had not been signalled already.

Although Mr Brown has spent another summer of frustrated silence, at least he knows there is no alternative credible candidate. The authoritarian populism of the Home Secretary, John Reid, has won plaudits in some right-wing newspapers but makes him an even less likely figure to triumph in a Labour leadership contest.

So we know Mr Blair will be going and that Mr Brown will take over. For politics, this is an astonishing amount of knowledge about the future. What no one knows is the context in which Mr Brown will assume the crown. Will the Labour Party be torn apart by the time of the succession? Will the new leader be perceived by too many voters as a return to a vote-losing past? These are the really big questions. The answers will determine whether Labour can win the next election.

Over the summer, the Chancellor has come in for private criticism from some of his increasingly impatient supporters for his lengthy period of silence. One ally of Mr Brown paid a holiday visit to Scotland this month, bumped into several despairing Labour figures, and came back concluding that "Gordon is in trouble". The frustrated supporters want Mr Brown to spell out in more detail his distinctive agenda now.

Oddly, they have an ally in Mr Blair, or at least they do on one level. Privately, Mr Blair believes that Mr Brown must say what he would do as Prime Minister in advance. In Mr Blair's view, Mr Brown cannot arrive in Downing Street and then unveil a series of policies and initiatives with little warning.

The problem, though, for Mr Brown is that he is trapped. There are limits to what he can say before the substance is lost in a blizzard of stories about division and open splits between Chancellor and outgoing Prime Minister. In such an unusual situation sometimes silence will be the best policy.

Not that he will, or should be, silent for much longer. A book of his speeches will be published shortly with endorsements from figures that are safely deified. They range from Nelson Mandela to Alan Greenspan, the biggest of big tents.

I am told that Mr Brown will also adopt a higher and more distinctive profile in the autumn, partly because he fears that the entire Labour Party is becoming tainted over the issue of "trust". Mr Brown watched in silent alarm as the apparently successful intelligence exercise, possibly foiling a terrorist attack, resulted in a drop in support for Labour this month. In the past, support for governments has tended to rise at times of apparently well-managed crisis.

Mr Brown has become gripped by the need to prove that a Labour government can be trusted once more, and will apparently make interventions with that objective in mind. Even so, he walks a high-wire act. He might find the circus is not worth performing in any longer if the next few months are dominated by increasingly public differences with the Prime Minister.

But the state of the circus will be determined more by Mr Blair's most ardent followers. Again various Blairites brief patronisingly and with unjustified self-confidence that they plan to lock Mr Brown into a series of reforms before the succession takes place. Some talk of policy initiatives, vaguely defined, that will shape Labour for the next 10 years. The former cabinet minister, Stephen Byers, leads the way for a group that becomes more evangelical as it declines in size.

Mr Byers wrote an article yesterday in which he stated: "There will be some who try to turn the clock back; to promote a set of priorities that plays to narrow, sectional interests rather than those that have a broad and popular appeal." The familiar metaphor of the clock being wrenched back in time risks framing Labour's internal debate in a way that could prove fatal. In this version, there are some dynamic forward-looking Blairites and the rest that are apparently looking to return to the 1970s. Who are these people? Mr Byers says he was referring to some left-wing union leaders, but as the rest of the article focused on the need for the next spending review to be taken away from the "anoraks in the Treasury", the writer appears to have had the Chancellor in mind as well.

This takes some chutzpah, considering that Mr Byers' contribution to the next spending round was a proposal made earlier this month, in which he called for the abolition of inheritance tax, without stating where the cuts in public spending cuts would fall in order to pay for it. His proposal was forensically dismissed across the political spectrum, from more rooted Blairite MPs to The Spectator . A senior figure in Downing Street joked that "Steve probably wrote it only to annoy Gordon", a sign at how damaging attacks aimed at Labour's next leader can be frivolously viewed at the top of the Government.

In seeking to claim that every vague idea they float represents the "future", while others are stuck in a mythical past, Mr Byers and his friends play into the hands of Labour's opponents. On the basis of what has happened during the seemingly quiet days of August, it is the extreme Blairites that risk losing Labour the next election.

s.richards@independent.co.uk