I have served in the House of Commons as a Labour member for 41 years, and I would never have dreamed of saying this about any one of my previous leaders. But Blair is a man who has disdain for both the House of Commons and international law.

This is a grave thing to say about my leader. But it is far less serious than the results of a war that could set western Christendom against Islam.

The overwhelming majority of international lawyers, including several who advise the government (such as Rabinder Singh, a partner in Cherie Booth’s Matrix Chambers), have concluded that military action in Iraq without proper UN Security Council authorization is illegal under international law. The Foreign Office’s deputy legal adviser, Elizabeth Wilmhurst, resigned on precisely this point after 30 years’ service. This puts the prime minister and those who will be fighting in his and President Bush’s name in a vulnerable legal position. Already lawyers are getting phone calls from anxious members of the armed forces.

Blair accuses opponents of war of “appeasement” — in spite of the fact that, in many cases, their active opposition to Saddam’s dictatorship well predates his. (I signed the 1987 early day motion against arms exports to Iraq. Blair and Gordon Brown didn’t.) If anyone is the “appeaser” it is Blair, in his support for the US government’s pre-emptive attack on Saddam.

I am not anti-American. I was a member of the executive of the British-American parliamentary group. I share at one remove four times over a grandmother with Harry S. Truman, and I hope to attend the celebrations in Missouri in May to mark the anniversary of his birthday.

But many in this country think the fundamentalists now running the White House are using Blair’s support as a fig leaf against their critics. It is useful for these people to say to their opponents: “But a British Labour prime minister supports us.”

If Britain had made it clear months ago that we would not be party to a US attack on Iraq, US public opinion itself might have stopped this war.

Many in the Labour Party believe Blair has misunderstood the pressing danger. It comes not from Iraq, but from terrorism. If there is a link between Al-Qaeda and Saddam Hussein, it is this: Osama Bin Laden hates Saddam Hussein. On at least two occasions Bin Laden’s organization has tried to assassinate Saddam. The effect of this war, however, could well be to bring the pair together. This is a war that will strengthen terrorism. I don’t think that Blair really understands the horrors of modern-day warfare. In 1994 I visited Baghdad (all expenses paid by me) and saw the carbonated limbs of women and children who had been impregnated against a wall by the heat of just one cruise missile. In the current war, hundreds of cruise missiles have been launched just to soften up the enemy.

We are told that the US intends to use incapacitating bio-chemical and depleted-uranium weapons. We are receiving information that the it intends to use war in Iraq as an opportunity to test out a range of weapons — cluster aviation bombs with self-guided munitions and pulse bombs being examples.

The UN was created in response to the indiscriminate horror of modern warfare in the 1940s. The UN Charter describes its role as saving “future generations from the scourge of war”. Surely that means that all those who claim to uphold the UN Charter should pursue peaceful solutions to their limits? The draft work plans of the UN weapons inspectorate make clear that the inspectors believed they could have made real progress down their non-violent path to disarmament. The Labour Party will not tolerate a leader who takes the country into an avoidable war. As Napoleon and Hitler found with the snow at the gates of Moscow, so Blair and Bush might find that the biggest weapon of mass destruction they encounter, before the gates of Baghdad, is the sun. They might be wise to pull out troops now, before they are cooked in the sands of the desert while laying seige to the city. They may lose political face; but the careers of Bush and Blair are of little consequence compared to environmental mayhem and military agony.

(Tam Dalyell is Labour MP for Linlithgow and Father of the House of Commons. A longer version of this article appears in Red Pepper magazine.)