The 45-minutes dispute threatens to discredit one of the most moral of wars

There is an irony. If Tony Blair were asked to summarise everything that was wrong with the old Labour Party he might well use two words: "Tony Benn." Yet, at least in foreign affairs, the Prime Minister has become the Bennites' greatest ally. Despite their efforts, the cause of anti-Americanism, anti-Westernism and pacifism did not flourish. Even before the 45-minute degringolade he had already done more than the Bennites ever could to undermine the British people's faith in American foreign policy. Now Mr Blair has given such doubts an enormous boost.

You are the Prime Minister. You are told that Saddam might possess deadly weapons deployable within 45 minutes. How do you respond? You ask urgent questions. What is the risk to Israel, Kuwait, the Saudi oil field, the friendly Gulf states? Could Saddam hit our bases in Cyprus? Can we be sure that the UK mainland is invulnerable? Is there a danger that Saddam's agents might smuggle the stuff into Britain and then detonate it? Confronted by information on a WMD threat, any prime minister would ask the obvious questions and persist until he was satisfied with the answers.

Yet Geoff Hoon now tells us that the only reason why he knew the truth about the 45-minute claim and the PM did not was that Mr Hoon asked out of curiosity. Now that he is not needed as a scapegoat, the Defence Secretary seems happy to act as a lickspittle, but he will have to raise his game. Curiosity: you do not need to possess exceptional inquisitive instincts to take an interest in the threat of WMD within 45 minutes. Only two attributes are required: an IQ of over 60 and as much sense of curiosity as the family tortoise. Is Tony Blair really so contemptuous of most voters' intelligence as to think that they will swallow this ridiculous story?

The truth is self-evident from the quotes and e-mails uncovered by the Hutton inquiry. At the time of the September dossier, Alastair Campbell and Jonathan Powell wanted to ensure good headlines. As the 45-minute claim was the sexiest point they had, they stripped out the caveats and highlighted it in a misleading way. They did so with little fear of the consequences because they and their boss were confident that after the invasion some form of WMD would be found, to guarantee more good headlines. A few recalcitrants might still have tried to make trouble about the 45 minutes, but as long as WMD could be produced such cavillers could be ignored.

That is not going to happen. The danger now is that the destruction of Mr Blair's credibility will inflict collateral damage on the support for the Iraq war. On that there are two basic points. The true case for war did not depend on Saddam's possessing WMD. Equally, the failure to find such weapons does not mean that it was wrong to go to war pre-emptively, so as to ensure that he never acquired them. Without the invasion, Saddam might have remained in power for another decade, or longer. With the passage of time, the risks of him obtaining terrifying weaponry were bound to grow. He would not have needed much in order to destroy the strategic balance in a fragile region.

As long as he was in power, that fragility could not have been cured. Much of the Middle East would have been doomed to continue as a geopolitical slum, where the people's prospects were decaying as the oil wealth was wasted. Saddam may not have had direct links with al-Qa'ida, but he and they were part of the same terrorist syndrome.

Aspects of American policy can be criticised. There was not nearly enough planning for the post-invasion phase. Much of the Bush administration approached the problem in too idealistic a spirit, with a blind faith in the Iraqi people's capacity for spontaneous regeneration. Moreover, elements of the administration seemed reluctant to acknowledge that justice for the Middle East must include justice for the Palestinians. Unless the problem of the settlements is addressed, the "road-map" will remain a pious aspiration and the Americans will be stigmatised as hypocrites throughout the Arab world.

That difficulty is growing. In previous decades, it was easy to exaggerate the rest of the Arab world's preoccupation with Palestine. A lot of Arabs disliked and distrusted Palestinians; many Arab sophisticates despised Arafat - and most Arabs live a long way from Nablus or Ramallah. But things are changing. These days many more Arabs, especially the young, identify with the Palestinian cause and condemn the US. Whatever happens in Iraq, it will be hard to persuade them that the Americans are not imperialist oppressors. Without progress over Palestine, it will be impossible.

Mr Bush himself has been more outspokenly in favour of a just arrangement for Palestine than any previous president. In an election year, however, there is little chance of changing the rhetoric into reality. We will just have to hope that he does recognise how important Palestine is to his plans and that once re-elected - the most likely outcome - he will devote to it all the energy of a determined man who will never have to fight another election.

But a free Iraqi state is just as important as a Palestinian state. If Saddam had remained in power the Palestinians would still have had a claim on statehood, but without the same political and moral momentum. The logic of their own position has forced the Americans to address Palestine. Without Iraq, George Bush would not have made nearly so many speeches in favour of a Palestinian state.

The war on Saddam was intended to be a catalyst for the reconstruction of much of the Middle East in the interest of its people. It is easy to see why Tony Blair was attracted to the idea, less easy to understand why he felt the need to conceal the fact. There was a moral case to be made, and he used to seem good at making moral cases, back in the days when he could declare that he was a pretty straight kind of guy without universal hoots of laughter.

Yet there was never any depth behind the morality. During his premiership Tony Blair has been confronted by three great challenges: the reform of the public services, British membership of the euro and Iraq. On each, the arguments that he favoured could only be have advanced by decisive moral leadership. Each time he failed to provide it. Despite the sanctimony that comes easily to him, it is as though he really lacks moral self-confidence. If so, he is justified.

As a result, however, a lot of the British people would no longer buy a used war from this man.Some of the parents and wives of our dead soldiers are ceasing to be sure that the men they loved fell in a just cause. Such doubts inflame the pain of grief. Yet they are not justified.

This was one of the most moral wars that the United Kingdom has ever fought. But due to Mr Blair's folly, it is in danger of being discredited. Other politicians must work to ensure that the discredit ends up where it belongs: not with the war itself, but with the Prime Minister who defamed it.