Language is, the sages tell us, intrinsic to being human. Or to what humans call “being human”, anyway. And yet, notwithstanding the 70-odd muscles and half a billion brain cells deployed every time we open our mouths, we hardly give the matter a second thought.

A couple of summers back, I spent an entire term with an idling history teacher who watched, in his many, many free periods, the entire back catalogue of QI on his laptop. And gave us running updates. Much as we mocked him for his pseudo-intellectual thumb-twiddling, in a staff room full of chat about timetables, syllabuses and the iniquities of the tuck shop, the regular injection of dorky trivia – and the entrenched and bitter arguments it provoked – was very welcome.

When a celebrity lets their public mask slip, something wonderful and also disconcerting can happen: they can noticeably become someone else. If they’re lucky, that change can be so marked that they become just another face in a crowd.

Cambridge University, cradle of Newton, Keynes and Wittgenstein, of Wordsworth, Turing and Tennyson, has produced 15 prime ministers and more Nobel Prize-winners than most nations. In its 200-year history, the university’s debating society has hosted princes, politicians and leaders in every field: the Dalai Lama, Winston Churchill, Nelson Mandela, and last week a 25-year-old east-London DJ, Kissy Sell Out.

There’s a surreal sitcom waiting to be written about the often-told story of when Charlie Higson and Paul Whitehouse were Stephen Fry and Hugh Laurie’s plasterers for a while in the early 1980s. Here’s the pitch: F and L would play caricatures of themselves in the mould of the posh twits they played in Blackadder, and – for extra comic frisson – H and W would play it straight while appearing (as the story goes) naturally funnier than their professional Oxbridge comedy-writing superiors.

Is there anywhere Stephen Fry will not go? I mean in documentaries. We’ve had Fry on depression and Fry on America, Fry on HIV and Fry on endangered species. Movingly, we’ve had Fry on who he thinks he is, an odyssey in which he discovered that much of his family fetched up in the gas ovens. Fry on Wagner? Admit it, you weren’t surprised. You didn't think, not another bloody comedian investigating, in pursuit of ratings, a subject of which he knows next to nothing. Fry, as everyone knows, knows everything.