PMQs verdict: A feelgood Commons senses spring in the air

Last week Ed Miliband put in a lacklustre performance which saw him overshadowed from all quarters. This week, having obviously studied my damning verdict carefully, he tried something different. Ed Balls nodded solemnly as Miliband outlined the sad tale of a struggling east Londoner called 'John'. He was a banker, Miliband explained with his tongue firmly in his cheek, whose bonus would be restricted to a mere £2 million under EU plans. Labour MPs were shocked. Their leader was trying to be funny! After waiting for two-and-a-half years, their relief flooded out in a great roaring cheer. I have a three-week-old baby and am nervously waiting for him to smile for the first time. When he does, I expect I will feel something akin to the emotions on the opposition benches this lunchtime.

David Cameron, not accustomed to this sort of treatment, should have been stymied by this unexpected development. Instead he came out with a new tag with which to rubbish Miliband. He was the "croupier in the casino when it all went bust". A Tory poster campaign is surely in the offing. This one could run and run. Miliband, standing up, grimaced in an agonised microexpression which made clear he realised how potent and damaging the jibe could be. Later in the session, Cameron expanded it to include Balls.  The "croupiers", he mocked, who had been giggling to each other moments before, turned stony-faced. Naturally, the Tory backbenches loved it.

The raised game from the two party leaders proved something of a relief, even if their main spat over the impact of the bedroom tax proved – well, taxing. Cameron struggled to get past Miliband's carefully calculated policy attack, hoping that repeatedly using the word "exempt" would get him past what Miliband called "basic arithmetic". There are only so many times the prime minister can declare his opposite number to be "completely wrong". Cameron, retreating to broader points about the big-picture housing benefit headache, looked like he was losing the argument.

He had to rely on good humour, too, to get past a couple of irritants this week. Rumblings about the leadership aspirations of leopard-skin-loving home secretary Theresa May were picked up on as an aside by Miliband, who said he was looking forward to "facing her in opposition". Then came Martin Horwood, the Lib Dem MP who is far more pugnacious than his mild-mannered bank manager demeanour suggests.

He invited Cameron to welcome Mike Thornton, the new member for Eastleigh, who was elected despite strenuous Tory efforts last Thursday. "Even governing parties can win marginal by-elections if they stick by their leader through thick and thin," Horwood noted, struggling to contain his glee as Thornton waved awkwardly beside him. Cameron was happy to welcome him, "for the period of this parliament". I'm sure he will enjoy making a contribution to our debates and I note very carefully the rest of his question," he chortled.

More was to come, from the sartorially inspired Sir Bob Russell. This Lib Dem legend was sporting a "splendid" bright orange waistcoat which – at the prime minister's invitation – he revealed as featuring a large Liberal Democrat logo on its breast. The look on Russell's face as he got his party logo out for the lads is simply impossible to describe.

That, of course, followed his unexpectedly helpful question. "The Lord sayeth go forth and in Eastleigh Labour came fourth," Russell began, bizarrely. On Ukip, he wondered how those Tory-Ukip electoral pact talks were going. "It was a good, honest and fair fight in Eastleigh," Cameron replied. In a week when fresh leadership plots emerged and his party was humiliated into third place, Cameron was displaying some impressively robust chutzpah. He added: "But what I would be absolutely clear about is the party that is supposed to be challenging as the party of opposition went precisely nowhere!"