PMQs began with a tussle over Universal Credit. Jeremy Corbyn’s team of wordsmiths and brainstormers had spent the morning ransacking a thesaurus for words meaning ‘destructive’. They found ‘broken, damaging, dangerous, callous, cruel, punitive and vicious.’ They added ‘very cruel’ for good measure.

These were the labels Corbyn applied to Universal Credit. ‘It should go,’ he urged. As for ‘very cruel’, he spoke of ‘the very cruel and callous two-child limit which caps benefits for larger families.’ Now that Britain’s parents have received this warning, they can avoid the ‘very cruel’ cap by capping their fecundity.

Boris replied with a set of cheerful statistics about economic growth and rising employment. He swerved off-piste to quote a poll revealing that a hefty chunk of Labour members consider Corbyn ‘the most popular Labour leader ever’.

‘That sentiment,’ gloated the PM, ‘is warmly shared by many on this side.’ Not a great joke. A bit too prepared. He was expecting the usual howling blizzard of indignation from the SNP’s Ian Blackford. So he launched a pre-emptive strike. ‘I see he’s about to rise to his feet,’ said the PM, ‘like a rocketing pheasant.’

Laughter (and a few gulps of outrage) were heard. Blackford paused, basking in the uproar. His backbenchers heckled across the aisle. ‘Desperate liar! Desperate liar!’

Meaning Boris, presumably. For the umpteenth time, Blackford belted out his scripted oration. ‘Devolution is under attack from this Tory government! Powers are being grabbed back to Westminster. There is no respect for the people of Scotland!’

Boris replied by denouncing the SNP’s perverse desire to sabotage the union. Blackford rose again and gave the foghorn another blast. ‘The devolution settlement must be respected... Stop the attack on our parliament!’

He complained about the result of the 2016 referendum. ‘Scotland said No and we meant it.’

Bit of a mistake. He’d exposed his chin and Boris bopped him straight back. ‘I agree!’ said the Prime Minister, ‘Scotland said No and they meant it. "No" to independence in the 2014 referendum which they were told was a once-in-a-generation vote by Alex Salmond and his protégé, Nicola Sturgeon.’

At these names, Blackford made an odd gesture, waggling an open palm like a toddler in a crib, as if pleading, ‘what about me?’ Boris added that the shipyards at Rosyth and Govan would be imperilled by secession.

‘We support industry,’ he scoffed. ‘They support nothing but manufactured grievances.’ More SNP-bashing was to come. But first Caroline Nokes gave Boris the chance to do a spot of improv. She asked about flooded waterways in her constituency and she urged him to ‘get out his plunger.’

Boris, without hesitation: ‘She can be assured that the ministerial Dyno-Rod will be deployed to sort out the blockage she was experiencing’.

The SNP’s Angus MacNeil expressed his fear, (or hope perhaps), that the UK economy will collapse outside the Single Market.

‘Trade-deals will only claw back one-thirtieth of the cost,’ he announced confidently. He must be clairvoyant. The negotiations have barely started. Boris fired back that Scotland does 60 per cent of its trade with the rest of the UK, and that the SNP will end up digging border-posts at Berwick-upon-Tweed.

‘And the pensioners of Scotland will have their pensions denominated in a new currency whose name they cannot even specify.’

During this MacNeil made hand-gestures, as Blackford had done. His fingers aped the prattling of a puppet. Both these men aspire to run their own state. A bit of statesmanship might help.