John Maynard Keynes was cremated and so he cannot, by definition, be turning in his grave. He doesn’t even have an urn because his ashes were strewn over the Sussex Downs. But if he did have a grave, or an urn, he’d be twirling away, for Prime Minister’s Questions was all about him yesterday – and not in a good way. Indeed, at one point I thought Gordon Brown was going to shout: “My Keynes is better than your Keynes!” Yes, it was that grown-up.

The Prime Minister, who counts Keynes, dead or alive, as among his closest advisers, continues to flourish as the world economy goes down the pan. Yesterday he was positively frisky when he popped into PMQs, a tiny interruption in his world tour. (Surely the words that presidents everywhere fear the most are: “Sir, I have Gordon Brown on the phone and he insists on talking to you.”) David Cameron does not look frisky. He still looks slightly stunned at the turn of events. But, if it’s any consolation, George Osborne looked worse. Yesterday David and George, two men normally joined at the hip if not by the Bullingdon Club, weren’t allowed to sit together. Instead William Hague separated them, although the two boys talked across him most of the time.

Dave began by booming on about whether Gordon would admit that he had not abolished boom and bust. Gordo boomed back: “We have had the longest period of growth in the history of this country.” This seemed a bit out of date to me, but then I don’t know Keynes.

They had a fight over the fiscal rules, with lots of shouting and the occasional “It’s not fair” type of squeal. “You were the man who was going to end the Punch and Judy show,” cried Gordo, his outrage as fake as the blood on a fangs of a Hallowe’en vampire.

Dave, furious, shouted back: “You say you want us to listen. We’ve been listening for ten years about your fiscal rules. You have stood there and lectured us about the brilliance of your fiscal rules. Why won’t you now admit they are dead?”

The Tory scream track was deafening, but it seemed only to inspire Gordon, who now whipped a quote from Dave that appeared to back Gordon. “You said, ‘Borrowing is inevitable and you have to allow that to happen. These automatic stabilisers, as Keynes calls them, those have to operate’!”

Perhaps it was the word “Keynes” that did it. Perhaps it was the automatic stabilisers. I thought that stabilisers belonged on bicycles, but I now find that Keynes got their first and that, in his multiplier model, they can be summed up as: multiplier = 1/(1- [ MPC(1- T) - MPI]). Yes, I know, flash.

Whatever it was, Dave went ballistic. “You have been going round telling everyone you are the new John Maynard Keynes with your plan for a spending splurge. Are you planning a splurge?”

Gordon, positively glowing, for he has known that he was the new Keynes for ages, shouted merrily back: “I thought – you were quoting Keynes! – I thought you said you supported Keynes and the automatic stabilisers!”

Dave, who loves bicycles, took this personally. “You haven’t got a plan!” he cried. “You just have a giant overdraft!” To which, Gordo riposted: “The Conservative Party says borrowing is the wrong approach. I say it is right!”

Or, as I believe it can be translated: “My Keynes is better than your Keynes – so there!”

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