As we endured the latest round of this miserably one-sided fight, my mind turned to the two men sitting to the left of their respective leaders.

It’s a decent bet (the double pays 22/1 with Paddy Power) that George Osborne and Tom Watson will be the next leaders of their parties, and will one day be squaring off against each other on these Wednesday lunchtimes, which would at least be more unpredictable.

Tom was doing his usual thing today, or at least his usual thing since he became Jeremy Corbyn’s deputy: utterly silent, smiling inscrutably, a look of faint amusement and utter detachment on his face.

The only times his lips tightened were when a backbench MP used Corbyn’s gaffe-a-thon with Andrew Marr on Sunday to allow the Prime Minister one of several free and gleeful hits on Trident, secondary picketing, and the Falklands, the latter a comradely gift from the DUP’s Nigel Dodds.

Obviously it wouldn’t do for Tom to smile when David Cameron is shoeing the poor, defenceless old man sitting next to him, but you wonder if these are also the moments when he realises Corbyn cannot go on much longer like this, and ponders being up at the despatch box himself very soon.

Diagonally opposite, George was having one of those days when people think he’s been at the mushrooms in St James’s Park. This is most unfair. George just suffers from the condition known as ‘Blissed Out Resting Face’: head lolling to his left, mouth agape, eyes dilated and staring blankly a thousand yards past Angela Eagle’s head.

You can tell George is on auto-pilot if he nods solemnly three times whenever he hears Cameron say the words ‘money’, ‘jobs’, ‘growth’ or ‘strong economy’, the way your brain automatically triggers an ‘Mmmm’ every twenty seconds when someone shows you their wedding photos.

Who knows where George’s head is actually at. Wondering how to help Marco Rubio? Planning his first reshuffle? Thinking about alternative endings for The Sopranos?

As for the main event, Corbyn stood up with the usual wall of noise in his face and void of silence at his back, and began in rather breathless form on the subject of student grants.

He was at least trying to show some punch in the first sentence of every question and comebacks, but each one then petered out feebly towards the end, like a mobile phone that goes through the motions of lighting up even when the battery is dead.

He introduced us to Liam, a maths teacher, and Vicky (or was it Vicki?), a would-be nurse, but their questions were swatted away by Cameron as easily as Corbyn’s own.

The problem is that “two out of three Vickis” get turned away when they apply to be nurses, said the PM, going on to inform us that “the British people want to train as nurses”. What, all of us?

He may be confusing ‘train’ with ‘dress up’, but perhaps the staffing shortages have got so bad that just wearing the uniform will do.

The fact is Cameron is now downright enjoying these sessions, and with good reason.

The one unfriendly question from a Tory MP – John Baron asking for a meeting about the EU negotiations – was treated with an insouciance bordering on contempt: “He seems to have made his mind up already, so I don’t want to take up more of his time than necessary.”

With nothing better to do on their side, two up-and-coming Labour MPs from London, Wes Streeting and Tulip Siddiq, asked him to agree whether knife crimes were bad things and bone marrow transplants were good, then nodded enthusiastically along with Cameron’s answers.

Incidentally, we have reached the desperate stage where if any hitherto largely unknown Labour MP stands up in Parliament, sounds vaguely coherent, and looks telegenic, they are immediately installed as a new leadership candidate, as soon as we can find out their name that is.

The only time Cameron was remotely tested today was when the SNP’s Angus Robertson enquired about some murky business in which we’re clearly up to our necks in The Yemen. But even then, the PM smoothly took out his spectacles, and read out word-for-word what the civil servants had told him to say to avoid misleading Parliament. Jack Straw take note.

There’s a simple reason Cameron is on such fine form, and he alluded to it when he responded to one of Corbyn’s questions by reading out a quote from “someone I rather miss, Ed Balls”.

For most of the PMQs since he’s been in office, Cameron had to put up with sledging in stereo, Ed Balls in his left ear constantly questioning his ability to do the job, Michael Dugher – sat on the step next to Dennis Skinner – doing likewise in rather earthier language.

Now they are both gone. The Prime Minister can finally hear himself think and talk, and there’s nothing he enjoys better than that.

To his left and right now, there are only the strange, mysterious silences of Messrs Watson and Osborne; two political samurai with a battle waiting to be joined.