The Sketch: A giddy chamber, a Tory leader and a gallows trapdoor ready to swing open

What an odd Prime Minister's Questions. The place was absolutely packed, straining at the rafters. All the galleries were stacked - press, public, peers. MPs stood five deep at the bar and crowded in behind the Speaker's chair. There was a sense of fatal anticipation in the House that spectators at a public execution would have recognised at once.

The Labour benches were in enormous good humour, cheering and laughing and waving their order papers as the leader of the Opposition walked across his front bench out onto the scaffold, or whatever they call it these days. And he, the sturdy fellow, he took their catcalls like a man, smiling, chuckling and making demotic gestures with his chin when necessary. The gravity of the situation caused a marvellous levity in the participants. Everybody knew that any hesitation, repetition or deviation made by the Tory leader would result in an oubliette opening up under his feet, causing him to fall and fall again, as far as it's possible for a man to fall, somewhere into the lost sewers of the Palace of Westminster. No wonder the Tories got into the swing of things, adding to the fiesta atmosphere in their own macabre way.

The first questioner rose. It was the Conservative Andrew Robathan. What an atmosphere he had to work with. Both leaders, you understand, are under quite extraordinary pressure. Mr Thing we know about. But that shouldn't obscure the fact that the Prime Minister is increasingly isolated, having lost most of his inner circle, facing a disintegrating Middle East, two very losable votes in the House and a fatal charge, from the last day of the Kelly trial.

Mr Robathan, with masterly sense of the political forces at work, asked about the failure to provide dental appointments in Leicestershire on the NHS.

The Prime Minister answered this and everything else with the same mixture of fact, fiction and quiet mendacity that are his well-established trademarks. In fact, all the old questions were asked and all the old answers were given (the blessed winter fuel allowance returned to the debate) and yet no one was really listening to the proceedings. The hubbub of conversation, heckling, random laughter, stupid jokes drowned out a full third of the session.

From what was audible, we should recognise Gisela Stuart who cleverly asked what qualities the Prime Minister would be looking for in people he wanted to appoint to the House of Lords. The PM made a joke and, in the confusion, told the truth: "Insofar as they are Labour members, ones who'll support the government." And Gregory Barker (who must be exceptionally clever to get where he has, as it certainly hasn't been on account of his looks) asked Mr Blair whether his back bench supported the Government's top-up fees policy or the Tories' no-fees policy. I couldn't see the Labour back bench's response to this, but I'm told they were writhing. This is the way forward: amiable and indeed supportive questioning can surgically detach Mr Blair and the robots from Mr Brown and the rebels. The Tory party is not the only thing in parliament starting to come apart on the dotted line.

simoncarr75@hotmail.com