A mood of giggles and mischief descended on PMQs today. David Cameron is in America – attempting to cure insomniacs by explaining Tory Euro-scepticism to them – and his role was taken by Nick Clegg. Harriet Harman, a notoriously sluggish debater, stood in for Ed Miliband. It’s said that when Harman trained as a solicitor she conceived such a high regard for the law that she went into politics instead.

Today she seemed as effervescent as last week’s Prosecco. She droned through a series of pre-scripted gags and less-than-sparkling jibes. This was one of her feeblest ever performances on the front bench. She started by mocking David Cameron for posing in a London bus while in New York. ‘That’s something he hasn’t done here.’

Then she asked why Cameron has attended PMQs only once in the previous eight weeks. Answer: the parliamentary calendar and the Thatcher funeral. Finally she invited Clegg to speculate on the PM’s hypothetical response to a division which is taking place in his absence. ‘Would he vote for or against? Or show real leadership and abstain?’

It’s hard to tell who she was trying to embarrass with these Christmas-cracker jokes. Herself or her back-stage writing poodles?

Clegg swiped her aside with casual irony. ‘She’s spent three questions pointing out that the Prime Minister isn’t here. What a penetrating insight into the affairs of state.’

He had more trouble from Conservative backbenchers. Peter Bone, a seasoned Lib Dem-baiter, took a bite out of The Clegg by asking him to confirm that the Tories are the only party offering an In/Out referendum.

James Gray reached up his sleeve and produced a vintage LibDem poster. ‘Only a real referendum will let people decide our country’s future,’ it said. Gray invited Clegg to join the choir of Tory rebels in the lobbies tonight as they gather to lament the absence of a referendum law from the Gracious Speech.

Clegg declined Gray’s blandishments and repeated his belief that a plebiscite should only follow new treaty proposals. This makes the referendum sound like a rehab programme. It only comes if the EU wants to change.

Edward Leigh aimed the meanest shot at Clegg. He brandished another old Lib-Dem leaflet which showed a referendum pledge alongside a mug-shot of Clegg. ‘Is this man a hypocrite,’ grinned Leigh, ‘or an imposter?’

Clegg smiled back. ‘That man – who I believe to be me – was stating something that my party has restated ever since.’

This was a confident, relaxed, front-foot performance from Clegg. He evidently enjoyed showing the Conservatives how little he cares if they pretend to like him or not. It’s better to face your accusers in open debate, and take their insults in public, rather than hearing them repeated at third-hand in shady corridors and darkened Westminster clubs. Clegg’s assured demeanour did him no end of good.

Politically he’s playing his cards with great care. He didn’t hold back when he attacked Labour’s front bench for messing up the economy, but he was more emollient towards their rank and file. When Labour backbenchers asked him why he hadn’t tackled a problem which they themselves had ignored while in office he accused them of ‘amnesia’. Nice word. Far nicer than hypocrisy which is what he meant. He’s in for the long-haul.

At first sight it scarcely matters that Labour failed to lay a blow on their opponents today. But their grassroots will be deeply unimpressed. If they can’t profit from Tory turmoil during a shambles like the present one, what kind of crisis are they waiting for?

Tags: Conservatives, Harriet Harman, Nick Clegg, PMQs, UK politics