John Rentoul: Will Gordon crash and burn?

He has taken the decision on the Bomb they want, but politics is unfair

It was the reaction to Gordon Brown's Mansion House speech that was the story, rather than the speech itself. Who seriously thought that a Prime Minister-Presumptive would have said anything other than that Britain's nuclear weapons should be retained? The reaction to the Chancellor's words is related to the national psychosis about football that Terence Blacker described last week. He wrote about the suppressed rage and disillusionment with which the English watch the World Cup: "It is as if we know that it will soon be ending in tears ... When defeat happens, there will be a sort of orgasm of collective despair, combined with something very like relief."

It involves a particular kind of doublethink. People simultaneously believe that England are destined to win and bound to lose. Similarly, people believe both that Brown will be utterly and transcendentally different from Tony Blair and that he is a sell-out traitor who offers only more of the same. The common criticism of Brown on nuclear weapons is that he has "failed to make the argument" for a radical reappraisal of Britain's place in the world. The idea that he might have failed to make this argument because he does not believe it escapes the likes of Clare Short, who is the natural representative of those members of the Labour Party who are always looking for someone new to betray them.

A moment's examination reveals that the "new thinking" that Brown lacks the courage to think is, in fact, the old thinking of the Labour left that finally lost the argument in 1989, when Neil Kinnock abandoned the policy of go-it-alone nuclear disarmament. Last week, the usual suspects trotted out exactly the same arguments they have always made and which have always been rejected overwhelmingly by the electorate. Trident is very expensive. It is not genuinely independent of the US. And - this one is usually supposed to be the clincher - by what right do we renew our own weapons of mass destruction while telling other countries that they cannot have them?

The old-thinkers make much, for example, of the alleged hypocrisy of the Government in telling Iran that it cannot take the next step towards acquiring nuclear weapons. Unfortunately, the curious priorities of many of the same people have recently been exposed by their devoting much energy on the internet to proving that Mahmoud Ahmadinejad, the Iranian President, was mistranslated: he did not say Israel should be "wiped off the map"; he said it should be "eliminated from the pages of history". So that's all right, then.

Just as unsurprising as Brown's support for replacing Trident is his backing for the building of new nuclear power stations. Blair had already taken the heat on this particular "betrayal", so there was less fuss about Brown's apostasy. It took the form of a three-word sub-clause in an article the Chancellor wrote two weeks ago, which mentioned energy policy, "including new nuclear". As we report today, the formal government decision will be taken in a cabinet committee tomorrow, but what that decision would be has been clear since at least November 2003. That was when a Labour Party consultation paper asked: "If in later years it looks as though it is impossible to meet our carbon targets... should we keep open the option to build more nuclear power stations?"

It was, and is, a good question. The problem that the green opponents of nuclear power have is that, if global warming is the most serious problem facing the planet, how can they argue, when it comes to nuclear power, that the issues of waste, catastrophic risk or cost are even more important? It is all very well Sir Menzies Campbell saying that we should use less energy, but however little energy we use, nuclear power would always reduce carbon emissions even more.

But what good does it do Gordon Brown to be right? Just as in football, when England's unbeaten run through the group stage is regarded as a prelude to disaster rather than a cause of pride, the psychology of pre-emptive disappointment is dangerous. David Cameron leads in the opinion polls on the basis of nothing more substantial than a winning manner and an insincere promise of a green future. The Conservative policy on nuclear power, for example, will be interesting. My guess is that it will be to replace some nuclear power stations as they reach the end of their lives, but fewer than Labour. That way Cameron can pose as "greener" than Brown, even if a strictly logical green campaigner, concerned about climate change, would say that he was not.

This was always going to be a difficult period for Brown. In Westminster last week his supporters were pleased by Clare Short's attack on him, because it makes him look less left-wing. But at the same time, he is desperate to convince people that the grass really is greener on the other side of a stable and orderly transition. His supporters speak hopefully of how he will "open out" once he is safely in No 10.

Unfortunately, that never seems to happen. All the recent evidence is that politicians confirm rather than confound the doubts about them when they achieve high office. Neil Kinnock, Charles Kennedy and Menzies Campbell were all at their best when they basked in the warm glow of admiration without responsibility. All their known faults became worse when they entered the confines of party leadership. Gordon Brown is not going to change. He will still be the politician who made an important announcement about the future of Britain's nuclear deterrent at the end of a 90-word sentence beginning with the word "And" in a speech in the City about the economy.

So I still disagree, respectfully, with my colleague Alan Watkins, who argues on page 37 that Alan Johnson will not beat Brown to the succession because all the previous Stop Gordon candidates crashed and burned. That is no guarantee. On the politicalbetting.com website last week, someone asked if they should bet their £10,000 pension lump sum on Brown for a "nearly certain" 38 per cent return. The consensus among the gamblers was "No", because politics is simply too uncertain.

Politics is much worse than that, of course. It is unkind and unfair. Brown has taken the decisions about this country's nuclear future that the voters want, and yet I fear that they will not reward him.