Had David Miliband disowned the Iraq war during the summer-long Labour leadership campaign, he would now be leader of the Labour Party. I can't prove it, but, Nick-Robinson-style [2], I feel it in my "gut".

So it's rather ironic that the shadow foreign secretary, a prickly and insecure politician to begin with, and reeling from the shock of such a narrow defeat at the hands of his kid brother only 72 hours earlier, should choose the Iraq passage of Ed Miliband's conference speech to inadvertently reveal to the world his (understandable?) irritation and frustration at the current state of affairs. The clip from ITV News [3] seems to show him saying, to a clapping Harriet Harman:

You voted for it, why are you clapping?

Bizarre. Did he not realise that journalists and photographers would be watching his every facial expression throughout the speech, to try and catch him looking unhappy? Here's a title for a future book: "Why do intelligent people do such stupid things?"

Harman's answer, however, is key:

I'm clapping because he is the leader, and as you know, I'm supporting him.

If Miliband decides to stay on in the shadow cabinet — and, like others, I doubt he will — he would have to internalise this rather crucial point. He is not leader. Ed is. Oh, and he got Iraq wrong, Ed (in private, if not in public) got it right.

But, the truth is, if he does decide to stay on, the media will spend the next five years looking for splits/divisions/rows between the two brothers. For the sake of Ed's leadership and the future of the Labour Party, this "giant" [4], to quote my colleague James, has to walk away from the front bench and, I would assume, parliament, too. (Is there an IMF or EU position becoming vacant in the next year or two??)

On a side note, those of you who criticise journalists/columnists/bloggers for being ultra-cynical and suspicious about politicians and their various public statements and motives (eg, Jeremy Paxman's "Why is this lying bastard lying to me?"), should pay attention to the David Miliband story.

Here is a politician who spent the entire campaign saying again and again that he had no plans to quit front-line politics, even if his brother beat him. He told me in an interview for the magazine [5], in mid-July:

I'm not walking away from the people of South Shields. I'm not walking away from the Labour Party . . . I'm very happy to serve under anyone.

And on the Politics Show on BBC1 three weeks ago, he mocked me as a journalist of "infinite impatience" for daring to suggest that he wouldn't be able to serve under his younger brother. Asked by me to give an explicit, on-air guarantee that he'd stay in the shadow cabinet under an Ed Miliband leadership, he said:

Of course. And I am absolutely clear about my intentions, my assumptions, and I answered that very, very clearly.

I guess we'll see if my journalistic cynicism (and impatience!) is vindicated at 5pm.