DID Tony Blair lie? Did he actively conceal the illegality of the Iraq war from the Cabinet and parliament?

Did he lie about weapons of mass destruction in Iraq? This is the paramount question of this extraordinarily election.

The Tory leader Michael Howard is in no doubt. Tony Blair is a liar - a serial liar. A leader who could lie about going to war, the most important decision any prime minister takes, is no longer fit for office.

Yet it is interesting how few Conservative politicians I speak to are prepared to use the "L" word, even about Tony Blair. It is the most serious charge you can make against a politician, and is an immediate resignation issue in the Commons.

In fact, it is very hard to prove that Tony Blair lied about anything. Every statement the Prime Minister has made about weapons of mass destruction, about the legality of the war, about regime change has been carefully sourced to some independent authority.

It was the Joint Intelligence Committee which said that the evidence of WMD was extensive and authoritative, when in fact it was patchy and sporadic.

Nor did the PM actually lie about Lord Goldsmith's opinion on the legality of the war. The attorney general stands by his March 17 opinion that the war was justified.

Now, I'm not trying to make the case for Tony Blair's defence here. He will have to answer to history for taking Britain into an unnecessary and probably illegal war in which tens of thousands of people died. However, it is too easy just to say that the PM lied.

It's much worse than that.

Something sinister took place in the inner sanctuaries of government to persuade reasonable people to draw unreasonable conclusions from questionable evidence. It was creative management of the truth, not actual falsehood, that took us into this war. It was the politics of presentation elevated to a principle of government.

Under New Labour's philosophy of government, anything that isn't actually a lie is true. Labour's moral relativists regard truth as the handmaiden of political expediency. You don't accept truth, you create it.

Something like a lengthy lawyer's opinion on the legality of the war in Iraq is not seen as a tablet of stone, but rather as a text which can be deconstructed, analysed, shaken down and reassembled - much as a journalist would deconstruct a speech to ensure that it tells a story which fitted the editorial agenda of the paper.

Yes, we hacks started it. Example:

Tony Blair once caused a huge row by comparing the Scottish parliament to a parish council. In fact, what he said was that, since any parish council raises taxes, there is no reason why the Scottish parliament should not do likewise. The newspaper story was not untrue, even though it was a gross distortion.

That is a very extreme example, but it illustrates what I mean by the creative management of the truth. Truth is something you use to win an argument, not something to bow down before.

Gordon Brown is one of the most creative truth-tellers of all. He famously presented - by crude double and triple accounting - a severe tightening of spending limits in the first three years of the 1997 Labour government as a massive increase in spending on health and schools. In fact, Brown intended to increase spending by less than John Major had.

The Chancellor's promises on tax in the last parliament were of a similar order. He promised not to raise income tax. He insisted that the government had no reason to increase national insurance contributions. Then he went ahead and increased national insurance by the equivalent of one penny on the pound in income tax.

When it came to the war in Iraq, the PM and his staff deployed all the skills they had honed over years of creative news management. The war was a done deal. The problem was how to justify it before the law and parliament.

The attorney general's detailed account of the highly questionable legality of the impending invasion was not going to satisfy the public, let alone the generals who worried they might be classed as war criminals. So, by deft selection and trimming, the document was turned into its opposite - an unequivocal declaration of confidence in the legality of conflict.

However, Goldsmith had to be squared. He had to agree to his highly qualified opinion being boiled down to a gung-ho endorsement.

Now, the attorney general had said that, while regime change was not a legal justification for an invasion without a second UN resolution mandate, the war could still be justified if there was a real and present danger to British national security and if there was conclusive proof that Saddam had been in "material breach" of UN resolutions on disarmament. The spin machine went to work to provide Goldsmith with what he needed. Unfortunately, there wasn't much evidence of either.

No serious military analyst thought Saddam was in any position to attack Britain. He had no delivery systems.

Moreover, Hans Blix, the UN weapons inspector, had told the UN that Saddam was engaged in serious disarmament.

"These aren't toothpicks, " he said, referring to the al Samoud missiles which the inspectors had seen dismantled.

Blix pleaded for more time, so that his team could establish whether there were any weapons of mass destruction left in Iraq from 1991. Blix suspected that there were. So did the late weapons inspector, Dr David Kelly. They were fairly confident that quantities of VX nerve gas, botulinum and other chemical agents were still kicking around Iraq. They suspected too that Iraq was trying to get a nuclear weapons programme off the ground. Nobody thought that Saddam had stockpiles of WMD which could be used to attack Britain.

However, a selective reading of Blix's reports, in particular his observation that Iraq was still not complying fully with his inspections, provided firm evidence that Saddam was in "material breach" of UN sanctions.

The Joint Intelligence Committee, moreover, had evidence from - as it turned out - a highly unreliable source in Iraq that Saddam had battlefield weapons that could be used within 45 minutes of an order being given, which could possibly carry chemical agents.

Throw all this together, and a capable newspaper journalist could easily turn it into a horror story that Saddam had weapons of mass destruction which he could use against Britain in 45 minutes. That's the story the editor wanted, after all. The London Evening Standard duly splashed with the 45 minute claim in March 2003 in the run up to the Commons debate.

It was a grotesque distortion. But no lies had been told. It was all true. There were WMD unaccounted for in Iraq, therefore there must be WMD in Iraq.

Saddam is not complying, therefore he is in material breach. He has weapons, therefore Britain was at risk.

Lord Goldsmith had his evidence of material breach, so - logically - he had to drop his caveats and qualifications and judge the war legal. The Cabinet was informed of this deadly threat and MPs given scary stories of impending armageddon. They duly voted for the war on March 18.

Thus an ageing dictator who had no WMD whatsoever, who posed no threat to Britain and who had been complying with UN weapons inspectors and actively disarming his only remaining delivery system, was deemed to be a threat to global peace.

Nothing lies better than the truth.