It may sound perverse to say so, but Tony Blair's critics, from the BBC in the centre to the saluters of Saddam Hussein's "courage and indefatigability" on the far right and left, have done the Prime Minister a favour. Their rage has unhinged them and let him off the hook. Blair is Bliar, according to the dopes behind the Stop the War Coalition; or a man who overruled the honest public servants and ordered them to put their name to propaganda that "they probably knew was wrong", according to the Today programme. Instead of seeing the Iraq war for what it was - a collective failure of government - the opposition created a false dichotomy between the lying spinners of new Labour on one side and the truth-seeking spies of MI6 on the other.
Blair was always going to beat that rap. Lord Butler asked why on earth the Prime Minister would have lied before the war when his lies would have been exposed as soon as the war was over. His question answered itself. Blair would not, nor would any other canny politician. In a less deranged climate, people would have realised that, even if the accusation had a grain of truth, the accusers would have needed John Scarlett, chairman of the Joint Intelligence Committee, and Sir Richard Dearlove, the head of MI6, to turn into whistle-blowers to substantiate it. You do not get to the top of the Joint Intelligence Committee or MI6 if you are suspected of harbouring a secret desire to wash the establishment's dirty linen in public.
No one felt the need to prove that Margaret Thatcher and John Major had overruled Treasury civil servants when they took the pound into the Exchange Rate Mechanism. Not even their most bitter critics claimed that they lied when they said they believed they were guaranteeing future prosperity.
The politicians, the civil service and, although they like to forget it, virtually all the City and media pundits were just wrong, monumentally wrong, and their errors destroyed the Conservative government. Why can't Blair's opponents be content with the same devastating judgement? Perhaps there has been a subliminal need to silence a nagging voice of conscience by coming up with the worst possible explanation of Blair's conduct.
For the first time in its history, after all, the liberal left was recommending that a people should continue to suffer under a fascist regime, a stance that takes some explaining. For whatever reason, it ought to have been enough to say that Blair had made a gigantic mistake, but somehow it was not.
The Butler report is not the whitewash that commentators predicted. Its findings reinforce the lesser charges against Blair, and would have done for leaders facing a halfway decent opposition. For those who want to understand, Butler goes some way to explaining how Blair got Iraq so wrong.
The report has unintentionally moving asides. "Iraq was a very difficult target," the report says. That is putting it mildly. The penalties for espionage were torture and execution, as my former colleague at the Observer Farzad Bazoft found. When in the 1980s Paul Henderson, as an executive with the Matrix Churchill engineering firm, volunteered to go to Iraq for MI6, its officers gave him a copy of Kanan Makiya's Republic of Fear, the best and most terrifying account of life in Ba'athist Iraq, as a warning of what would happen to him if his cover was blown. (Readers with long memories may remember that, in an act which shamed even the unembarrassable Tories, Henderson was falsely accused of selling arms to Iraq when he made it safely back home.)
The last great Iraqi intelligence disaster before this great Iraqi intelligence disaster was in 1996, when the CIA and MI6 convinced themselves that they had come up with a water-tight plan to engineer a "quick, simple coup". Senior officers in the Iraqi army, Republican Guard and Special Republican Guard were organised into a high-level conspiracy. They were provided with money and the most secure satellite communications available. A palace revolution which left the military in charge seemed the perfect way of achieving that great goal of nervous statesmen, a stable transfer of power. The plot was infiltrated by Saddam's forces from pretty much the moment of its conception. They bided their time and waited for more and more officers to incriminate themselves. In all, they arrested 800 people. Most died under torture, and a few brave souls went to their graves without incriminating others. In a neat final touch, the Iraqi secret police used the west's own satellite phones to transmit a parting shot to the CIA: "We have arrested all your people. You might as well go home."
Which about summed it up. Inevitably, given the ferocious penalties for the merest suspicion of disloyalty, hardly anyone in Iraq was willing to spy. Before his suicide, David Kelly wrote that the only way to be sure Saddam Hussein had disarmed was to overthrow Saddam Hussein. This looks like a point in Blair's favour, and in many ways it is - but it can be turned on its head.
After the gruesome successes of Saddam's legions of secret policemen, why did anyone have confidence in the intelligence that got out? Butler says that MI6 did not follow the neoconservatives in Washington, DC in believing the stories of Iraqi exiles. For all the sneers against those refugees from tyranny by westerners who could not have coped with a fraction of their suffering, the exiles had an obvious motive for wanting to provoke the US into overthrowing Ba'athism.
None the less, Butler shows that the sources MI6 had in Iraq were few and unreliable. In the jargon of the espionage bureaucracy, a "validation of human intelligence sources" took place after the war when MI6 was able to get into Iraq and check whether the intelligence it had given government was true. The results were dispiriting. One MI6 source gave valuable information on some issues "but on others was passing on what he had heard within his circle". The reports of a second source on chemical and biological weapons were "open to doubt". A third agent's claims were found to be such nonsense that MI6 belatedly withdrew them. And so it went on. Only two MI6 contacts passed the postwar tests and of them Butler says "it is notable that their reports were less worrying than the rest about Iraqi chemical and biological weapons".
It is not hindsight to point out the flimsiness of it all. David Kelly told Susan Watts of the BBC that he could not believe the sloppiness of the MI6 debriefing of the Iraqi spy who said that Saddam had weapons ready to fire in 45 minutes. Did it mean that missiles could be assembled in 45 minutes? Or loaded with chemicals in 45 minutes? Or what? "I mean," sighed Kelly, "I've no idea who debriefed this guy. Quite often it is someone who has no experience of the topic."
Possibly it was asking too much for MI6 to go to Tony Blair and say that its sources were too scarce and dubious to provide reliable intelligence, but that was the truth of the matter. The spies told the politicians what they wanted to hear, and not just because they wanted to please their masters. The world's intelligence services had been shocked after the Gulf war of 1991 to discover that Saddam Hussein was far closer to building a nuclear weapon than they had suspected.
Saddam had launched two unprovoked wars and a genocidal civil war. He had been given the benefit of the doubt earlier, with disastrous consequences for others. Those who appreciate the ironies of history have already noted that he was finally overthrown on the one occasion in 30 years in power when he deserved the benefit of the doubt.
"We detected a tendency for [intelligence] assessments to be coloured by overreaction to previous errors," says Butler. They were also coloured by a desire to please the Americans who were going to go to war regardless.
If the premiership of Tony Blair survives, and it remains open to question if he will be make it to the next election, he will be able to thank his opponents in part. They were determined to prove that he was a liar rather than a blunderer. They were determined to prove that he had forced the intelligence services to deceive the public when in truth the intelligence services had deceived themselves.
They set the bar impossibly high and were dazed when they cracked their skulls on it.