Gordon Brown did a spectacular U-turn yesterday as only he can. One moment he was going full steam ahead with his plan to tax the poor more and the next he was outraged at the very thought of anyone perpetrating such a wholly despicable act.

At first it reminded me of someone who utters a swear word and then slaps himself for saying it. Except Gordon didn’t slap himself for, of course, he won’t admit to saying it. So instead he accused David Cameron of saying something worse and slapped him.

Oh yes, what a happy slappy PMQs it was. It was so verbally violent that someone should have filmed it on a wonky mobile and posted it on YouTube. The ferocity of Gordon Brown took me by surprise, though I knew, when he flashed that strange stretchy-lipped smile, that something was up.

I looked at the the Chief Whip, Geoff Hoon, and saw that he too was smiling (and giggling). Clearly the whips had been busy. The official climbdown on the 10p tax band battle had been signalled an hour earlier, via a letter from the Chancellor. Labour MPs, mutinous the day before, were now poised to scream their total adoration. They make lemmings look wayward.

Up jumped David Cameron. “I think we can call this session Prime Minister’s U-turns!” he shouted into a wall of Labour sound.

The smile got even stretchier until I thought his lips would break. “We were told there would be no backdown, we’ve had a backdown!” attacked Dave. “Is he making these changes because he thought he’d lose the vote next week?”

Gordon lunged forward. “We have said for some time that we want to do more to help people on low incomes.” And that, actually, was about as close as he ever got to admitting anything. There was no apology, no admission of error. Instead, he launched a broadside against the Tory party, the cause of all poverty. At this, Dave screamed right back: “Does the Prime Minister have any idea what a pathetic figure he cuts today?”

And they were off. Dave stabbing away, his logical ice-pick pumping away like mad. Gordon was a spectacle of stubborn fury. When he gets like this, he is not so much a man as a weather system and, as Dave and his perfectly argued ice-pick were finding out, it’s hard to beat a hurricane.

MPs circled the fight, rumbustious and unruly. The Speaker had to intervene often, at one point looking over at a sniping Jack Straw. “The Lord High Chancellor is too noisy!”

Mr Straw covered his face with his hands. “It’s not often you have to give the Lord High Chancellor an ASBO!” trilled Dave.

The opposition leader was scathing, quoting Labour MPs saying bad things about Gordon. He noted that the Labour peer Lord Desai had described the Prime Minister’s leadership style as being like porridge. “Another week like this and it will be Cheerios!”

MPs went Fruit Loopy over that, but only briefly. Soon Gordon was indulging in one of his brag-a-thons. Did you know that he and Labour have done more to stop poverty than anyone in 100 years? It was quite shameless.

So who won? Neither Gordon nor Dave really, who ended up locked together in sort of exhausted stagger. Of course, there is always the poor, the 5.3 million people ostensibly at the centre of this storm. But don’t count on it: this was about politics, not poverty.

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