Jonathan Agnew recently described off-the-record interviews as those where you agree that it’s ‘between you and I’. Last month, Jess Phillips tweeted that she had ‘read a few wild accounts of Boris Johnson and I in the lobby’. And a Times journalist wrote about someone who had ‘made Jenny and I feel so welcome’. All three are articulate, intelligent people. And yet all three wrote ‘I’ where they meant ‘me’.

It’s happening more and more. The only explanation can be self-doubt. Give any of these people a second to think about it, and they’ll reply that yes, of course they should have said ‘me’. It’s easy to work out: just remove the other person from the sentence. You’d never say that so-and-so ‘would make I feel so welcome’. Yet somehow the ‘I’ epidemic is spreading. People hear others saying it, and begin to feel — against everything they know — that they should say it too.

It’s like one of those experiments in which respondents are asked which of three lines on a piece of paper is the longest, not knowing that the other people in the room are actors primed to say ‘C’ rather than ‘B’. You’d be amazed how many people give in and, even though the evidence is there in front of them, say ‘C’ too.

You can understand why it’s happening with ‘and I’. We’re scared of the mistake in the opposite direction — as in ‘Terry and me went to the pub’. We’ve all been taught that it should be ‘Terry and I’. Plus we’ve heard the Queen say ‘my husband and I’ a lot. So we begin to use ‘and I’ even when it’s wrong.

But my point here is not to campaign in favour of the correct usage. It’s the opposite: I want to reject the notion that there’s such a thing as ‘correct’ English at all. What’s fascinating about the spread of ‘and I’ is that it reveals our worry that there’s some pristine set of objectively provable rules with which we’re failing to comply.

But language isn’t like maths, where you can categorically show that two plus two is four. Language has no fundamental rights and wrongs, only conventions. These have been evolving ever since the first caveman and cavewoman directed a few grunts at each other. And they’re evolving still. You cannot definitively prove that any are ‘right’ and others ‘wrong’.

In fact some are downright illogical. ‘Its’, for instance. There’s a certain sort of person who, on discovering you’re a writer, says: ‘No doubt you’ll be like me, you’ll be very keen on children learning proper grammar and punctuation.’ Instead of giving my instinctive reply — ‘Oh sod off, you old bore’ — I ask them to explain why ‘its’ as a possessive doesn’t have an apostrophe. It’s fun watching them flounder. The answer, of course, is that there is no answer. It’s probably just some arbitrary hangover from a mistake someone made centuries ago, rather as Covent Garden was a convent with a garden until someone accidentally missed out the ‘n’. (If you do have an answer about ‘its’, by the way, I think you’ll have gathered enough by now to save yourself the ink.)

There are also times when correct English just sounds absurd. Take ‘I’ itself. My partner’s father used to ring up and announce: ‘It is I’. God rest your slightly pompous soul, David.

If you really want to experience the lunacies that arise from a belief in correct language, look at Ofsted. Primary school children now have to be taught that ‘inverted commas’ is right, while ‘speech marks’ is wrong. (Actually it might be the other way round — if I gave a monkey’s I’d look it up.) You and I know that those terms are interchangeable. You and I — and the child who looks at those marks on the page — can see that both make perfect sense. The child will also be perfectly relaxed about calling them ‘speech marks’ even when they’re not surrounding actual speech (as when I used them just then). That’s because a primary school child is more intelligent than the Ofsted cretin who came up with this ludicrous rule.

As the excellent teacher who told me about the new rule pointed out, it’ll no doubt be flipped around in a few years’ time, and the ‘incorrect’ term will become the ‘correct’ one. But the truly horrible thing about an education system like this is that it destroys children’s love of language. It tells them they have to worry about rules, instead of encouraging them to read and write for its own sake. Let them read for fun and they’ll absorb the rules — or conventions — anyway. Have them shaking in fear about English tests, and you’ll reinforce their insecurity about getting language ‘right’.

Then one day that insecurity will have them saying ‘and I’ even though they mean ‘and me’.