Last week, Sir Keir Starmer was lethal.This week Boris Johnson made him furious.

What changed? Starmer’s questions became slightly too long, which made it easier for the Prime Minister to pick and choose which aspects of this vast subject to tackle.

And Johnson looked and sounded better than he did last week. He had come to the Chamber determined to counter-attack, and did so immediately, by saying of Starmer, “he doesn’t seem to have remembered”.

An annoying jibe, for Starmer has an excellent memory. He in turn suggested that Johnson had “rather missed the point…I’m quoting the Government’s paper…”

But Starmer did this at excessive length. He yielded to the temptation to produce more evidence of the contradictions in the Government’s position than was required.

Johnson, woundingly: “He’s simply in ignorance of the facts.”

Starmer proceeded to suggest, again at excessive length, that no effective tracing system has been in place since 12th March: “That’s a huge hole in our defences, isn’t it, Prime Minister?”

Johnson said he had briefed Starmer on what was going on: “I think his feigned ignorance really doesn’t come very well.”

Starmer the Just was being accused of bad faith. Johnson also urged him to abandon “his slightly negative tone”.

These were wounding imputations. Starmer was by now very angry. He observed that 31,000 deaths is negative, so “of course I’m going to ask about that”.

But the faint imputation of negativity hung to him for the rest of the session. He asked why NHS workers who have come from abroad have to pay “the deeply unfair immigration health surcharge”.

Johnson treated that question with respect: he conceded that NHS workers from abroad had saved his life. But he concluded that “with great respect…I do think that is the right way forward”.

The Prime Minister had refused to be pushed round by Starmer. One cannot yet know whether the credit Johnson gets for being tough will outweigh the blame he gets for being hard-hearted.

But one could begin to see how he intends to defeat the man who last week humiliated him. Starmer, the new line goes, has a “brilliant forensic mind” – words used by Johnson today – but unfortunately he is also negative, disingenuous and soft.

At one point, the Speaker, Sir Lindsay Hoyle, uttered a fierce rebuke to Matt Hancock, the Health Secretary, for heckling Starmer – another way in which the Tories hope to neutralise the Leader of the Opposition.

If Starmer has any sense, he will treat these elaborate counter-measures as a compliment. The Tories are taking him seriously, and the next time he takes them on, he should mock them for it.

We shall have to wait a fortnight, until after the Whitsun Recess, to see whether he can follow that counsel of perfection.