In one purblind, puritanical phrase, Jeremy Corbyn showed why he will never, except by accident, be any good at Prime Minister’s Questions.

David Cameron had just tried to amuse the House by quoting from the wonderful list in today’s Times which places Labour MPs in five groups: “core group” (the 19 who are most loyal to Corbyn),  “core group plus” (56), “neutral but not hostile” (72), “core group negative” (49) and “hostile” (36).

A well-informed left-wing journalist this morning assured me these figures are too favourable to Corbyn: his MPs are actually even less loyal to him. But even without that adjustment, the list was sure to prove irresistible to Cameron.

How did Corbyn prepare himself against the mockery which was bound to fall on him? It is not the task of this column to attempt to improve his feeble performances.

But it shouldn’t have been beyond the wit of man, or even the wit of Corbyn, to remark that Iain Duncan Smith was not on anyone’s list, but has shown what the Tories think of Cameron.

Cameron finished his sallies about the list – which had not come across quite as well as he hoped, for Labour backbenchers broke the flow a bit by shouting “IDS” and other insults across the Chamber – with the line, “I thought I had problems”.

Instead of assuring the Prime Minister that he does indeed have problems, Corbyn said in a starchy tone: “If I could invite the Prime Minister to leave the theatre and return to reality.”

What madness! The theatre is reality in heightened form. Great theatre tells the truth, and so does great political theatre.

Lincoln at Gettysburg told the truth, and told it so well that he made an imperishable impression on his listeners and on every later generation. For Lincoln the great moralist liked nothing better than to go and see a play, and was in love with words.

Corbyn no doubt considers the word “theatre” to be a synonym for frivolity, escapism, illicit pleasure, idle diversion and all the other things of which Puritans so disapprove that as soon as they could they banned it.

But theatre can be done in any number of different ways, from the most tragic to the most comic, or any combination. And PMQs only works if it is dramatic: if the issues of the hour are condensed into a very few words, and heightened for effect.

Some of us had hoped that like one of the kitchen sink dramatists of the 1950s, Corbyn might achieve great things, and force Cameron – for fear of being seen as a orotund relic of the past – to raise his game.

Corbyn could, as it were, become the new John Osborne: except that Corbyn himself didn’t even want to try that, and was certainly not going to hire anyone who might help him to write the lines needed to get under Cameron’s skin.

It is perfectly true that the theatre of PMQs is often badly done, and can degenerate into a low-grade version of Punch and Judy.

But the answer to bad theatre is good theatre, not no theatre. Corbyn adds to all his other faults a self-righteous, narrow-minded determination to destroy the drama of politics. The sooner his comrades push him off a cliff, the better.