In the 1960s Masters and Johnson formulated their theory of human sexual response: they defined that divine crescendo as moving from excitement, through plateau, and on finally to the bliss of climax. This model is curiously applicable to parliamentary performance, in particular, to PMQs…

Jezza began promisingly, quickening the pulse of the House by leading on Windrush. We have come to expect Corbyn – labouring under a misbegotten impression of his own political creativity and genius – to question the government on the least (rather than most) pressing issue of the day. Were, for example, the nation to be overwhelmed by a robotic Tory killer army, literally stringing up the homeless from lamposts and throwing benefits claimants off buildings, Corbyn would use that week’s PMQs to lead on the abstruse calculus of the schools funding formula. As such, Corbyn usually fails to reach even the excitement stage. Diane, is that you sighing knowingly?

But not today. Corbyn even managed to arouse the passions of moderate backbenchers as it appeared he would come armed with a salvo of killer factoids to capitalise on this great embarrassment for the Home Office. Yvette Cooper would stage her own spotlight moment later in proceedings, but in the meantime she nodded along with Corbyn, the awkward squad all warmer than usual. By his third intervention, Jezza was well into the plateau phase. May strained and stressed, her voice becoming thinner:

“The Windrush generation are British, they are part of us and there will be a compensation scheme.”

Scant details on that, however, and disappointingly, no Cameronesque gotcha moment – true or untrue – as the Prime Minister so masterfully fired off last week. The cyclical, grinding shouts – somehow still in monotone – of Jezza still ploughing on, over and over again repeating his general, confected rage over Windrush, showed he was well into his rhythm. MPs, as bored lovers do, stared at the ceiling. What was this all leading up to? When would Jezza let go?

Then it came:

“The current Home Secretary inherited a failing policy and made it worse. Isn’t it time she took responsibility and resigned?”

All round immediate, awkward, sidewards glances. A collective, unfulfilled sigh of despair from the backbenches. Some Labour MPs turned away. Others faced the now flaccid specimen who had so suddenly gone limp at the despatch box – they faced him flush with anger. Corbyn “fluffed it”, one told me later. Try as Jez might, he could not manoeuvre his mouth with necessary skill and impact around the scripted words on the page. His failure was oral, muffling the line to such a degree that reporters were confused whether he had called on the Home Secretary to resign or on the Prime Minister to resign. In true Corbyn style, one bad line ruined six questions…

Jezza, as always, had failed to attain climax. Masters and Johnson were Freudians – they concluded that a man stuck in plateau phase is subconsciously anxious about his performance. Corbyn left his honourable members panting, confused, disappointed and unfulfilled. His elect-ile dysfunction had struck again. ‘Perhaps he should resign’, everyone thought, turning his zinger into a boomerang and throwing the crescendo into reverse. After all, if you can’t finish, what’s the point in starting?