When giving a speech at a school, there are many ways to endear yourself. You can turn up drunk and address the head teacher loudly and enthusiastically by the wrong name. You can allow your trousers to split at the back, or spill your glass of water, or fall head first from the rostrum.
All these strategies will earn you an appreciative round of applause. You can try to suck up to your audience by saying that you once experimented with cannabis, and, though you will find a surprising measure of disapproval, you will not forfeit their general sympathy.
But there is one taboo you must never break. If you should so much as breathe a word of scepticism about the number of A-grade passes awarded to the modern cohort of British schoolchildren, then you are for it, my friend.
If you should seem to harbour the slightest reservations about our amazing and continuous Soviet-style improvement at exams, you will find that there is a Batemanesque horror across the room. Your entire audience will look dumbfounded, like a bunch of baby bunny rabbits clubbed across the mazard.
Even as you are blurting out your horrible opinions you will find – as I found the other day – that the teacher in charge springs from his or her place to cut you off. It is all very well for you to say that, says the teacher, but how do you know that these marks are not accurate? Might it not be, says the teacher, that British children deserve to have more A grades than ever before? Might it not be the case that we, as a nation, are just getting cleverer and cleverer? Might it not be that children are more hard-working and better taught than ever before?
At this point, the teacher turns to the class and says, with a triumphant flourish, that mankind never ran a sub-four-minute mile until 1954, and that this feat is now accomplished regularly by thousands of people. Is it not possible that the same is happening in the field of education? she demands.
And then the audience of students begins to look at you threateningly, and a gurgling murmur of hate is heard, and stare wildly back, and you wish you had the facts at your fingertips.
So here they are…