It takes a very special courage, the sort only certain politicians possess, I suppose, to wait until someone is out of the room before speaking ill of him.

Having stood closely by George Bush's America these last few years as a trusted member of Tony Blair's inner circle, and then as Foreign Secretary, David Miliband yesterday chose the last 120 hours of Mr Bush's presidency to say what a disaster his foreign policy had been. The War on Terror was a “mistaken” doctrine that had united the West's enemies against us, he told an audience in Mumbai.

Thank you, David. You might have thought of saying that sooner.

Interestingly, if it's an attempt to curry favour with the incoming US President, it may be as misjudged as the Foreign Secretary's faint-hearted putsch against Gordon Brown last summer. From what I hear, though he has his doubts about some of the terminology, Barack Obama is going to tread very carefully before signalling any big changes in the broader US approach to the threat of terrorism, the seriousness of which he fully grasps as he prepares to take office.

Still, the daubing with yellow paint by Mr Miliband was a useful reminder that the encomiums won't exactly be flowing in for Mr Bush as he leaves office on Tuesday. In fact it's hard to find another two-term president who left office in such low esteem. Mr Bush's approval ratings among Americans have barely edged up from last November, when Mr Obama was elected, and remain near historic lows.

Around the world the Bush name is synonymous with arrogance, ignorance, reckless insouciance, torture, violence and ineptitude. And those would be from America's friends. He leaves office with his country facing the worst economic crisis since (take your pick) Jimmy Carter or Herbert Hoover left town, two of his predecessors now firmly ensconced in the presidential Hall of Infamy.

But before we consign him to a seat in the same dark palace, we should pause. The end of a president's term in office is never the best time to review his record.

Richard Nixon, the only president forced from office by something other than election or death, is regarded more favourably 30 years later, especially for his diplomatic achievements. Lyndon Johnson, pilloried for the Vietnam War and a broken man when he stepped down in 1969, is now rightly lauded for his civil rights record. Harry Truman left office to widespread disdain - in the midst of another messy war, in Korea. But he is now widely regarded as one of the best presidents, the architect of America's Cold War strategy.

Then again, we should quickly note that there's no fixed rule about this. Sometimes presidents who leave office to contemporary derision get the same raspberry from the historians years later: Presidents Carter and Hoover spring to mind.

So what is it to be for Mr Bush: a stunning revision of historical judgment some time in the future? Or will the next decade or so merely confirm how bad the world now believes him to be?

Mr Bush's presidency was and will be defined by the events of September 11, 2001. Any proper judgment on it must reflect not only how he responded to them but how those events changed America.

Out of a clear blue sky Mr Bush and all Americans woke up to the fact that they faced a danger the country had never confronted before: the possibility, indeed likelihood, of human destruction on an unthinkable scale by an enemy that moved largely unseen in their own midst. To complicate matters further, it was an enemy animated by a medieval religious ideology, rooted in the pernicious failure of Islam as a civilising force in the Middle East. It required a radical change in America's posture.

Defensively, at home, it had to move with great dispatch to forestall future attacks. Offensively, overseas, it needed to crush the seeds of the violence that threatened America.

Mr Bush's signal success has been the protection of the American homeland. Much of the angry criticism of him as a tyrant-torturer, the Master of Guantánamo, ignores this rather important fact. Any government in the US after 9/11 - Democrat or Republican - would have sought extraordinary executive power to manage the threat (just as the Democrat Franklin Roosevelt did in the 1940s). Some of the measures may have been excessive (just as they were then) and might even have been counterproductive. The West's infinite capacity for self-criticism certainly helped to nurture the angry grievance directed against it in much of the world.

But any proper accounting of the record must consider two things. First, that America has indeed not been attacked since 9/11. Second, that the age of terror requires a fundamental rebalancing of the equation between civil liberty and security - whoever is president.

Mr Bush's was mostly unsuccessful. Afghanistan started out well but, thanks in no small part to the delicate sensibilities of America's allies, has descended dangerously close to failure. Iraq was, for several years, a disaster, compounded by the self-satisfied assurances that all was going perfectly well. Only when Mr Bush had been brought finally to the brink of the abyss did he begin to understand the need for change.

And yet history might still judge that Mr Bush's political ideal - the eradication of the tyrannous political regimes that have nursed Islamist violence for centuries - was the right one. A democratic, pluralist Iraq, dismissed for years by Mr Bush's critics as a pipe dream, is much closer to becoming a reality, with large potential consequences for the security of the whole world.

The proper indictment of Mr Bush, then, is not the silly idea that he was some uniquely evil tyrant, seeking selfishly to enlarge the American Government's power around the world. It is that he was grotesquely, almost picturesquely, inept.

His Administration was disastrously unprepared for the consequences of toppling Saddam Hussein, genuinely believing, it seems, that democracy would fall happily into place. It is tragic that tens of thousands of lives had to be lost to demonstrate the absurdity of that naivety.

This ineptitude was later reflected in the response to Hurricane Katrina, and perhaps even more spectacularly and damagingly, over the response to the financial crisis in the last year, when Mr Bush's Administration has lumbered desultorily from one inadequate measure to the next.

This, sadly, is the probable Bush legacy. History may one day come to view more favourably the goals and ideals of America in the last eight years. But it will surely never forgive the execution.

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