Technical failings provided the recurring melody of today’s PMQs. The video-link played-up, delaying the second question from the SNP’s Westminster leader, Ian Blackford (the suspense was truly indescribable) in favour of West Bromwich East’s Nicola Richards. “Can you hear me?” she kept saying, under the impression we could not. Eventually Houston re-established contact with the Hebrides, allowing Blackford his second chance to condemn the prime minister only for the Speaker to get so bored by its long-windedness that he cut him short. That will be one more slight, marked, and committed to memory.

More importantly it was IT problems that were troubling the grand interrogator, Sir Keir Starmer QC. Ten days had elapsed since the revelation that the Home Office had mistakenly deleted criminal records, he reminded the near empty chamber. The losses included crime-scene data, DNA records and fingerprints. Among the “basic questions” he would have expected the prime minister to ask was how many criminal records were deleted?

The question was, of course, premised upon the expectation that bluffer Boris hadn’t even crayoned the answer on his inner cuff. And that seemed to be the case when the prime minister began – according to taste, reassuringly or evasively – with his belief that there was a high expectation that the lost data could yet be restored.

Starmer was ready for this, his trap about to be sprung. How many, he repeated? The prime minister rattled off, at suspiciously rapid speed, the figures of 213,000 offence records, 175,000 arrest records and 15,000 person records.

In the tone of voice that implied he was having to deal with a schoolchild of exceptional dim-wittedness, Starmer revealed that it was extraordinary that “he can’t tell us how many cases had been lost” because the figure missing from the police national computer was actually 403,000.

But as Dr Starmer, headmaster, spoke, the classroom dunce could be seen scribbling in his folder. Presumably it was just a doodle of a big slice of cake or a fantasy involving matron. So, scarcely taking heed, Starmer kept going, hammering home the point again that Johnson-major’s “basic” failure to keep up with the class and do the maths was unacceptable. Much more in this vein and Starmer might have asked his secretary to arrange an appointment with the idiot boy’s parents.

At this, Boy Johnson stopped doodling. “I’ve just done some maths briefly in my head” he announced. There was something in the manner in which he said this that suggested we were either about to be entertained by an answer of guileless stupidity or by the equivalent of the five-year-old Wolfgang Amadeus Mozart informing his father that he had composed a minuet and trio in G major and would papa care to hear it?

“If you add 213,000 and 175,000 plus 15,000” began the classroom dimwit on the cusp of being revealed as a boy wonder, “you get to 403,000 records.” There was the shortest of pauses before he continued, looking directly at his astonished headmaster, “if only he’d bothered to do that swift computation in his head, he would have had the answer before he stood up and claimed not to hear it.”

Dr Starmer stuttered on, but for the rest of the lesson he was the one listening for the bell.