Ten years ago this week I was in the process of helping Robin Cook resign from government. Most of the previous decade had been spent helping him to get into government and stay there, so it's fair to say that walking out in protest wasn't how it was meant to end. Cook certainly regarded Iraq as a personal failure, even though it allowed him to finish his ministerial career with the applause of parliamentary colleagues ringing in his ears. He would rather have won the argument against war in cabinet and seen his career fizzle out in the usual manner at a later date.
Cook's regret wasn't just about the war itself, although he correctly anticipated the immense human suffering it would cause. It came also from the knowledge of what it said about the kind of party Labour had become. This was no momentary lapse of judgement. The errors that led to the invasion of Iraq revealed the extent to which Labour had adopted priorities and working methods that should have been alien to its instincts as a party of the democratic left.
Countless books, articles and inquiries have detailed the distortions and omissions by which the Blair government presented a false intelligence picture of Iraq's weapons of mass destruction capabilities to the British people. But this was always servant to a greater falsehood - the idea that Labour's position had anything to do with Iraq at all. Until George W Bush decided that Saddam had to go, Tony Blair was content to stick with a strategy of containment. It was his desire to position himself as US ally no.1 that drove the change of policy. Had Bush decided to make an example of a different member of the 'axis of evil' - Iran or North Korea - Downing Street would doubtless have produced the case for why that country had to be dealt with.
Blair didn't have an Iraq policy; he had an America policy, and as a former senior official from the Bush administration confirmed again last weekend, it led Blair to offer the White House unconditional support for regime change come what may.
An often overlooked, but no less important, part of the story concerns the role of the cabinet and the Labour Party more widely in taking Britain to war. It is clear from the Cook diaries that he and Clare Short were not the only ministers to harbour serious reservations about Blair's approach to Iraq as it took shape during the middle part of 2002. Other voices of concern were raised around the Cabinet table only to fall silent as Blair's determination became clearer. As Jack Straw was candid enough to tell the Chilcot inquiry, he suppressed his own doubts out of loyalty to his leader. Something in the culture of the party prevented the checks and balances that define good government from working.
The Iraq War was the culmination of a process that started in 1994 with the rise of New Labour and reflected its heady psychological brew of arrogance and self-loathing. The arrogance came from a quasi-Leninist belief in Labour as the agent of some great historical mission on behalf of the masses - a traditional conceit of Labourism, admittedly. The self-loathing came from the party's repeated failure to fulfil that mission, ending in the crushing disappointment of 1992. The conclusion Labour drew from these competing emotions was that it must win at all costs. Power and truth became entirely instrumental to that goal. Anything that got in the way - policies, principles and people - had to be ruthlessly swept aside.
One particular New Labour innovation was to insist that the pursuit of power necessitated an alliance with the powerful - the financial and business elites, right-wing media barons and the White House (regardless of who occupied it). Labour didn't just have to neutralise their opposition; it had to win their approval whatever it took. The more painful the compromises the better, because it allowed Labour to convince itself that it was finally serious about winning. It became the ideological equivalent of self-harm for a party that secretly despised itself for the failures of the past. Success in 1997 completed the process by infantilising the Labour Party with gratitude to Blair.
These, then, were the essential ingredients of the Iraq disaster: an 'anything goes' approach to the truth, a slavish attitude to the transatlantic conservative elite and a party gripped by a cult of mindless leader-worship.
What, then, has changed to make another Iraq impossible? A fair amount, I would argue. Ed Miliband set out his criticisms of the war in 2010, but has sensibly avoided making it a theme of his leadership. It isn't the point anyway. As ought to be clear, Iraq was a symptom of what was wrong with New Labour, not the cause of it. The greater task is to replace arrogance and self-loathing with the humility and self-confidence Labour needs to be a successful force for change in the future.
I think real progress has been made. Miliband's willingness to set the agenda on press reform would be hard to imagine under another leader. His advocacy of radical banking reform, higher taxes on wealth and a foreign policy made in London rather than Washington are other welcome departures from New Labour. To be fair, the circumstances are much more favourable to this kind of approach than they were in Blair's day. The City discredited itself with the financial crash, Rupert Murdoch did the same with phone hacking and even David Cameron wouldn't touch the Republican Right with a bargepole. Still, Miliband deserves credit for being willing to take positions of principle that conflict with the interests of the powerful.
It is also good that Labour is now being led in a much more collegiate style. Given the circumstances of the 2010 leadership election, it might be argued that this was a necessity. But it also seems to reflect Miliband's personal preference. He doesn't marginalise and brief against colleagues that get in his way. He engages with them and tries to find common ground. This is a significant shift from the control-freakery of the past and the main reason why Labour has been able to defy its history by remaining united in defeat. It is essential if Labour is to govern more effectively in the future.
Labour still faces plenty of problems in coping with the legacy disintegration and decline that started with the Iraq War. But the lessons of the past are in the process of being absorbed. It's a great pity that Robin Cook didn't live to see the changes that are now being made. I think he would have been heartened by them.