What’s a polite way to say shut up and move on?

This is the thing about populism. It’s great when the majority happens to want the same things you want. Then it’s easy. Listen to the people’s anger! They must have what they want! If you don’t agree with the people, you’re an out-of-touch elitist!

The trouble starts when the majority suddenly wants something you don’t want. Such as – to pluck an example at random – the sacking of Dominic Cummings.

It isn’t just the Government’s critics who want it. According to polls, a majority of Leave voters want it, and a majority of Tory voters, too. Tory MPS have been swamped with emails from constituents indignant that, in their view, there was one rule for Mr Cummings and another for the public.

Boris Johnson, however, is still refusing to budge. He’s determined not to lose his most senior adviser. Which is why yesterday, via videocall, he faced yet another barrage of questions about him, this time from the Commons Liaison Committee.

The experience did not seem to delight the Prime Minister. In fact, he often sounded weary and impatient.

“This has been going on for several days now,” he grumbled. Several times he replied that he didn’t “propose to add” to what he’d said previously. And he repeatedly claimed that “a lot” of the “allegations” against Mr Cummings were “false”.

This puzzled MPS. Darren Jones (Lab, Bristol NW) asked him which specific allegations were false. Mr Johnson did not say (“I have nothing to add”). Meg Hillier (Lab, Hackney S & Shoreditch) asked him repeatedly whether he’d been shown evidence that allegations were false.

“If it pleases you, I will say yes, I did,” he replied, at the third time of asking. So, shouldn’t that evidence, whatever it was, be published, asked Ms Hillier, in order to clear Mr Cummings’s good name?

Mr Johnson, apparently, thought not. “I know there’s a great political interest in this… But I do think… I’ve said what I’ve said about the whole business… I think it would be much better if we could now move on…”

Move on. That was his key message. It was practically a catchphrase. He said it again and again, at least when asked about Mr Cummings. “I think what we need to do really is to move on… Time to leave it aside and move on… Move on…”

It’s a phrase politicians use when an unhelpful story refuses to go away and all other approaches are exhausted.

When saying it, though, it’s important to get the tone right. You have to make it sound polite and heartfelt – a public-spirited plea to your critics to consider crucial issues that are in danger of being forgotten.

You can’t afford it to sound bored or irritable. Otherwise, people watching – including people who have complained to their MPS – might take it as shorthand for “shut up and leave me alone”.