This was, as many things are, the fault of the party opposite. How typical of those Brownite enemies of enterprise on the frontbench to insist that every clause and commitment in the NHS new legislation to be personally explained by the man at the top. Couldn’t they see that he had enough on his plate, without answering their stream of endless, tedious questions? The sooner this unnecessary level of bureaucracy was abolished, the better!

Ed Miliband tried to contain his delight (and failed) as his boot rested on the prime minister’s throat, allowing only enough air for garbled, circular responses. David Cameron, normally an enviable communicator, temporarily forgot how to speak in sentences. The phrase ‘cherry picking’ sprang forth from his lips five times in just six answers. What did he mean? Lib Dem backbenchers looked on, ever concerned and always confused. Were these cherries ripe for picking? Were they growing in an organic orchard? Perhaps they should be privatised? And what did this have to do with GP commissioning?

Their questions, like Ed Miliband’s, went unanswered and the prime minister retreated to the comfort zone of parliamentary insults. Last week he had amused us with some rather cutting stuff about the older Miliband. Who knew what treats the crack team of joke writers at No 10 had cooked up for us this time? Cheryl Gillan could barely contain herself as the Tory benches fizzed with anticipation at the prospect of having yet another acidic putdown to smear on the faces of their unhappy Labour rivals.

Finally, deliciously, the moment was upon the House, as, after an agonising build-up steeped heavily in parliamentary cliché, Cameron pounced. Leaning forward onto the dispatch box he fired a shot aimed squarely at Ed Miliband’s heart, a deadly arrow of inarguable political wit, arcing gracefully across the chamber, felling all in its path. ‘What a pity’ the prime minister said confidently ‘that the leader of the opposition is … son of roadblock!’

For a moment, nobody knew what to do. Tumbleweed tumbled. Feet shuffled uncomfortably. Nick Clegg’s gaze wandered into the middle distance. The prime minister sat back down, looking pale and a little lost. Somewhere in Downing Street, a speechwriter started noisily clearing their desk, causing Ken Clarke to stir in his sleep.

The prescripted joke had not gone down well. In fact, only Ed Miliband was smiling.