Boris Johnson today struck a blow beneath Sir Keir Starmer’s belt:

“He needs to make up his mind what brief he’s going to take today, because at the moment, Mr Speaker, it looks as if he’s got more briefs than Calvin Klein.”

This was vulgar and disrespectful, and that was the point.

Starmer the Roundhead was endeavouring, as usual, to raise the tone, and convert Johnson the Cavalier into an honest, sober, professional Prime Minister who owns up to mistakes and promises in a penitent tone to do better in future.

The Prime Minister responded by hitting the Leader of the Opposition in the Calvin Kleins. It was unsporting, but was by far the most memorable image to come out of PMQs, indicating in the manner of a tabloid headline that Johnson refuses to take Starmer seriously.

If the sheaf of hand-written notes with which Johnson arrived in the Chamber is anything to go by, he is taking seriously the task of not taking Starmer seriously.

“This is such rhetorical nonsense,” Starmer had earlier protested, and one could see what he meant. The Oxford Union style is bound to strike him as disreputable.

But Johnson is a more formidable opponent than he may appear to those who are simply disgusted by his style. For amid the flouts and jeers, the PM ventures to tell some hard truths.

When Starmer pressed him on the loss of jobs at British Airways, and the attempt by that firm to force its remaining 30,000 staff to accept worse terms and conditions, Johnson refused either to support or to denounce such tactics.

But he did say the Government does not possess “a magic wand” with which it can ensure that every single job which existed before the pandemic can be preserved after it.

Starmer brandished some official report: “Has the Prime Minister actually read the report?”

“I am of course aware of the report,” Johnson replied. Here is a man with extensive experience of not doing the work his teachers said it was essential for him to do, who nevertheless ended up not just as Captain of School, but as Prime Minister.

Johnson, in short, is an affront to serious-minded people everywhere. They may, however, constitute a minority of the electorate.