Chaos in the Commons as Gordon Brown did something no one could have predicted. David Cameron had chosen the subject of Tibet (or Tea-bet as the PM says). Dave thought it was the perfect topic: obviously he cares deeply but also, crucially, it is the latest topic that Gordon has been dithering over.

And so Dave pounced. Mr Brown, he said, must confront China. His tone was a mixture of righteousness and hectoring. Even his bald spot, every week a few empty follicles larger, was imitating the shape of a halo. He sat back, ready for the typical Brownian answer that could be filed under “dither and delay”.

“I spoke to Premier Wen this morning,” began Mr Brown. At these words MPs started hitting their ears. What? The PM had done something! Where was the dither? And its evil twin, delay?

Mr Brown revealed what seemed to amount to his own Tea-bet Peace Plan. Plus, he has decided to meet the Dalai (which he pronounced Dial-eye) Lama when he is in London. The Tories started hooting like confused owls. No one had ever thought that the Prime Minister would announce an actual decision. We have heard him announce reviews, forums, working groups and national debates. But a decision? This was very special.

Dave was flummoxed. “Can I congratulate you on making absolutely the right decision!” It sounded hollow. Dave hates playing the sherpa. Mr Brown, who never gives an inch, shouted: “We make the right decisions at all times!”

So, at half-time, the score was Brown 3, Cameron 0.

But never count an Old Etonian out. They didn’t go to Eton to be counted out and, in the second half, Mr Cameron was back with a vengeance. He picked three of the many topics on which the PM is currently dithering and demanded that he make a decision, now.

But Mr Brown had made enough decisions for one day (his quota is one a month). Amid the dithering, he tried to turn the tables by asking Mr Cameron a question. “If you want to ask me questions,” snapped Dave, “call an election and you can ask six a week!”

In recent appearances Mr Cameron has perfected a technique beloved of stand-up comedians: he picks a member of the audience to humiliate. Last week, during the Budget debate, he plucked Ed Balls, the Children’s Secretary, out of the audience and accused him of shouting “So what?” Mr Balls shouted that he had been shouting “So weak!” No one, apart from Hansard, believed him.

Yesterday, Mr Cameron couldn’t resist. “Good to see the Children’s Secretary sitting there so quietly this week!”

This brought screams of joy from the Tories.

“SO WHAT?” they shouted as Mr Balls pressed his lips together.

“Very, very good!” cried Dave, playing the head teacher now.

Dave started to taunt the PM about the low-intensity warfare that has broken out in Downing Street. Dave noted that there was a new strategist at No 10 named David Muir. “I have done a bit of research on the internet. He has listed his favourite book . . .” The noise was overwhelming now and Dave paused, as much for comic timing as anything, before crying: “The book is called The Unstoppable Power of Leaderless Organisations!”

The audience, for that is what it seemed, collapsed with glee. Not so the Prime Minister, who unleashed a barrage. His hand sliced the air. It even, for a moment, formed into a fist and hit the dispatch box. The Great Clunking Fist was back.

Final score: Brown 3, Cameron 3. But Tea-bet may be a winner.

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