The Sketch: There's capital to be made out of Brown's financial confusion

The natural end for a beast as big and as bonkers as Gordon Brown is up the top of the Empire State building, swatting away biplanes. He roars and rails, he swipes his paws, but they come at him from every angle, pumping cannon fire. His grip on the radio mast must be getting weaker. Is it too late for flying lessons?

An idea has been quietly coalescing in parts of the media, left and right: Gordon is preparing an exit.

He gave that interview at the weekend, remember, saying how he could "walk away". Ed Balls gave it a little public nudge along on Monday, as well.

And for some weeks it has been quietly said that Mandelson will bump him – or cause him to bow out – at the spring conference and install Alan Johnson so that Labour can go straight into an election campaign.

In breaking news, if the Commons means anything, that date with destiny will be brought forward to the autumn conference.

Cameron slaughtered the old bruiser. Speaker Bercow had called (to some laughter) for a quiet, rational debate. That mended some fences with the Tories because quiet debate ruins the Prime Minister.

Quietly, Cameron kept coming back to the question of a central deception: how come Gordon's capital spending keeps going up, but the Government's Budget has capital spending going sharply down?

The Prime Minister roared. He babbled figures. He denounced Tory cuts to capital spending. He denied Labour cuts, then confirmed them, then denied his confirmation then post-denied his pre-confirmation. At least we understood what was happening to capital spending. It's going up. And down.

Labour rank and file looked on astounded. Their man had collapsed in front of their eyes. It was one long "Obama Beach" (as he'd called Omaha Beach, in front of the US President during the recent D-Day celebrations). He tried to say Ombudsman, he said Osborneman. He tried to say "the Polish Law and Order party" but he said "department". He tried to say Labour didn't believe in cuts, but he said Tories didn't believe in cuts. His figures came out backwards – in one data stream, spending rose between "1998 and 1992".

And his front bench sat there, more grieving than mourning. The corners of Douglas Alexander's mouth went down to his jawbone. Harriet looked dazed. Alistair Darling smiled a little Siamese smile as his master flailed and failed. And then Gordon sat down and leant across him AND Douglas Alexander to take advice from... the Tory defector Shaun Woodward. On the economy! That really was a Labour cut. Gordon cut his Chancellor in front of the Tories, his party and the television audience. That's how alone he is now.

NB: Speaker news. What an operator! He declared from the chair that ministers must no longer give policy to the media before Parliament. This collision course with the Government will infuriate the Labour front bench (but it doesn't matter what they think now) and please the Tories (or "the incoming government" as he sees them). It's going to be a very sketchable test of wills as the Speaker has the power to "name" – i.e. kick a minister out of the House. He must win. And he knows he has to.

simoncarr@sketch.sc