There's a lot riding on this session - the NHS, the troop surge, Iran, Copenhagen, financial regulation and the still ailing economy. It's a particularly important session for Cameron, who needs a strong performance to regain momentumk following a series of bad polls.
12:01: We're away with the Buthcer's Bill.
12:03: Labour MP Doug Naismith asks about the NHS cancer report. Brown points to independent regulators will mean that incompetent managers have no place to hide.
12:05: Here's Cameron - will the US troop surge mean that British troops can concentrate rather than extend their operations, a prelude to withdrawal no doubt. Brown doesn't answer the question directly, but says that the ANA are joining in.
12:07: Cameron responds by asking for clarfication about Obama's pledge to withdraw in 2011 and Brown's plan to begin withdrawal next year. Brown denies that he gave any such definite assurances, which to be fair is true. Advantage Brown.
12:08: Now Cameron moves onto firmer ground: the economy. Is the UK the only member of the G20 in recession? Brown repsonds masterfully: "No that isn't true... SPAIN is a member of the G20 and it is still in recession." Oh well that's cracked it, Spain isn't a member of the G20 - come on Cameron.
Now the 2 exchange blows about what they have and haven't done. Brown says that Cameron my sound like a modern PR man, but the voice is firmly in the 1930s. Cameron responds with: that must have sounded better in the bunker. Pretty raucous stuff and the backbenchers and the frontbenchers love it.
12:12: Has Brown got a credible route out of the budget nightmare we're stuck with. No.
12:13: At last, Cameron hits Brown where he should have done weeks ago. The only person who is committed to raising inheritance tax thresholds and has done so, is Brown. Brown has no answer besides a Prisoner of Zenda response that the Tory policy was dreamt up on the playing fields of Eton. Brown playing the class card more obviously this time.
12:15: Reese Witherspoon is in the House, campaigning against domestic violence. Brown praises the work of Renee Wetherspoon. Oh dear.
12:16: Nick Clegg's on his feet. Clegg praises Obama's plan, but wonders if a strategy that depends on President Karzai can work? It's this line again. Brown to be fair is on sparkling form, for a clunking fist, "I'm sure President Obama welcomes the leader of the Liberal Democrats' endorsement. Momentum is with him, no doubt.
12:18: Clegg's second question concerns local powers and local forces in Afghanistan, broadly the Dan Korski line. Brown says this is being considered.
12:20: Question to the effect why was the Lockerbie bomber released, more than 3 months has elapsed since his release. Decision of the Scottisk ya-di-ya-da-ya-da
12:22: Brown notes the Tories' doubts about AGW and hopes that he will receive cross party support at Copenhagen.
12:24: Brown says that the PBR will contain multiple clauses about funding a green future and funding for developing countries to do the same.
12:25: Tom Harris asks if MPs should pay tax in Britain. Yes, is Brown's reply. This session really could've gone better for Cameron.
12:26: Tory MP Greg Barker asks about Michel Barnier's appointment - how did the PM lose it for Britain? Brown denies that Britain will lose, despite Sarkozy's explicit comment that Britain will lose, saying that this is the advantage about being in the mainstream of the EU. Eh?
12:30: Tim Yeo asks a very peculiar question about the government's commitment to green taxes, he seems to advocate a rise on VAT on fuel specifically. Good God no. Brown deals with the question easily.
12:31: Sir Peter Tapsell asks the Prime Minister to resign. Brown thanks Tapsell for his advice, but regrettably chooses not to accept it.
VERDICT: Brown was almost garrolous and there is no doubt that momentum has shifted. This is particularly bizarre because Cameron is on top of the arguments and Brown has not enjoyed a bounce. The conclusion is that Cameron and the Tories are off colour, and Brown senses it. The word from within the bunker is that the boss is getting happier as an election draws near; he likes a fight. On the evidence of today's session that would seem true. A lot rests on Osborne's response to the PBR next week to reverse what has been a poor session for the Tories.