The debate in the House of Commons over Iraq yesterday had a surreal quality to it. Those who moved the motion had opposed the idea of the war and have always opposed the conduct of what happened. They would have disliked it irrespective of whether events since the fall of Saddam Hussein proceeded smoothly or, as has been the case, more tragically. Their ambition was not to empower a committee of seven distinguished individuals to conduct a forensic examination but to embarrass and, if possible, humiliate the Prime Minister. That the proposed timing of such a loaded inquiry was crassly poor was immaterial to them.

And yet, despite that, at least the likes of Plaid Cymru and the Scottish Nationalist Party have a redeeming consistency to them. They are of the fringe and not the mainstream and do not aspire to form a majority government in Britain at the next general election. They are parties of protest who would be sorely tested if asked to take hard decisions in a real world of frequently limited options. Much is the same for the entirely predictable cadre of left-wing Labour MPs who decided to back them yesterday.

The Conservative Party, by striking contrast, should always be different. David Cameron voted to support military intervention in March 2003 as did most of his colleagues. They did so in the full knowledge that this was a mission in which the United States would be the dominant partner — in military and political terms — and that almost all the decisions made about strategy during and after combat would be taken in Washington. A British prime minister would have a voice in those discussions, but could not wield a veto. The issue that confronted MPs three years ago was the principle of overthrowing the Iraqi dictatorship. Most Tory MPs assented and backed the Government.

So what on earth was Mr Cameron doing yesterday standing shoulder to shoulder with such bizarre allies? The same Mr Cameron who at the Conservative Party conference a month ago affirmed his stance that “when the Government is right, we will support it”? The Mr Cameron who, in his several previous opportunities to make a statement on Iraq, saw no need to ask for any inquiry on any timescale? The Mr Cameron who seeks to be seen to have the qualities of a prime minister?

The simple, shameful truth of the debate yesterday is that it was driven by spectacularly shallow opportunism. Everyone in that chamber knows that serious mistakes occurred in the aftermath of Saddam fleeing from Baghdad and that they happened in the office of Donald Rumsfeld at the Pentagon and not in Downing Street. There is an argument for a searching inquiry into this affair but it should be empowered and held after the bulk of US and British troops have left what remains a combat zone. That date cannot be predicted. The objective of such an exercise should be to learn lessons and not score cheap, partisan points.

In the end, the Commons flirted with stupidity but drew back from committing a stupid act. This was less an act of shared wisdom, nevertheless, than the result of a calculation by Labour MPs who did not want to hand their opponents a phoney parliamentary victory. The Government now has to press ahead with what needs to be done in Iraq, although this might well be unpopular in the short term with sections of the electorate. The principal Opposition has to learn to behave like a principled Opposition.