WHEN is a thigh not a thigh? When it’s a knee, of course. When is a lie not a lie? When it’s the answer to a question nobody is asking.

“The allegation is untrue,” said a Downing Street spokesperson on Sunday night, after a day of questioning about claims made by a Sunday Times journalist that Boris Johnson had groped her under a table in the late 1990s. The question is, which allegation is untrue? One made in the article, or a different one altogether?

Charlotte Edwardes alleges that during Johnson’s tenure as editor of The Spectator, he grabbed her thigh during a lunch. “His hand is high up my leg and he has enough inner flesh beneath his fingers to make me sit suddenly upright,” she wrote. She further claims that when she relayed this to her friend – who had been sitting on the other side of Johnson – the friend said he had groped her in exactly the same way.

The allegation is clear – that the now Prime Minister grabbed the thighs of two women under the table at a lunch in the 1990s. So why does it seem like Downing Street wants us to talk about knees instead?

“Boris Johnson DENIES claims he groped Charlotte Edwardes’ knee and complains he wants to talk about BUSES” tweeted the Daily Mail at lunchtime yesterday. Shortly afterwards, the word “knee” was removed from the headline, replaced with “thigh” – though crucially the original wording still appeared in the preview that was being shared on Facebook and Twitter.

The Mail weren’t the only ones who appeared confused about the basics of human anatomy. The Sun ran a story on its website about the thigh-groping claims, yet captured one of its pictures of Johnson with “Boris Johnson is accusing of squeezing a young journalists [sic] knee while editor at the Spectator”. The Guardian reported the Downing Street quote – “the allegation is untrue” – but added “sources said the quote related specifically to the allegation that Johnson put his hand on Edwardes’ knee.”

“Are you sure they’re different?” asked the Downing Street press officer when I called seeking clarification. Yes, I said. A knee is clearly different from a thigh. So which allegation is being denied? The one made by Charlotte Edwardes, about thigh-grabbing, or a different allegation about knee-touching? And why are we having to rely on “sources” to inform us about the context of Downing Street statements? As we went to press, no answers were forthcoming.

Some might say it doesn’t matter whether it was a thigh or a knee. After all, any touching without consent is unacceptable. But the truth does matter. The media deliberately downgrading allegations matters. Substituting “knee” for “thigh” could well be enough to change how some voters perceive the alleged incident. Those old, male Tory voters who believe that #MeToo has “gone too far”, and that you can’t even talk to a woman these days without getting into trouble, will doubtless be happy to file an incident of knee-touching under “clumsy pass” rather than blatant sexual assault. A knee-touch under a table could conceivably be an accident; a thigh-grab not so much.

They’ll doubtless have been further reassured by journalist Toby Young yesterday telling the Tory party conference: “Back then at The Spectator, in those raucous days, people complained if Boris didn’t put his hand on their knee.”

My National colleague Laura Webster has been keeping a close eye on statements from Number 10, and noting how references to buses and bridges are conveniently pushing stories unfavourable to Johnson (about the lie on the side of a bus, and the disastrous Garden Bridge project in London) down the search engine rankings.

This week, as people are using the word “model” to search for stories about the PM’s links to Jennifer Arcuri, the PM has described himself as a “model of restraint”. And this isn’t the first time he has spoken about models. In June, the then frontrunner in the Tory leadership contest delivered a bizarre ramble about his hobby of making model buses out of cardboard boxes. At the time, it was hard to explain this weird little performance. Now it’s all becoming clear.

When it comes to this week’s damage limitation, shoehorning the word “thigh” into a statement would be far too obvious – but who needs to resort to such methods when their pals in the right-wing media stand poised ready to flip the narrative?

Does it really matter what the full stories say, as long as knee-related content is trending on Twitter? In any case, there will surely be another scandal along in a minute. Don’t be surprised if it involves a ditch …