Back pain is a major problem for primary school teachers. One reason is teachers’ dreadful posture as they sink further down those low staffroom chairs when the head announces that the school is signing up to the Government’s latest wacky scheme (“Dowsing - we’ll be the first school in the country to do it!”). The other culprit is spending every day bent over miniature children’s furniture. The lower down the school you go, the more like Alice in Wonderland it becomes. For reception teachers, going home to normal-sized furniture must be like a rapid comedown from a particularly bad acid trip.

Further up the school, you can judge the age of a desk by how much graffiti has been scratched into it. This is usually quite tame stuff, inscribed by Year 6 leavers who, not being teenagers, have yet to realise that the correct use for desks is as a storage place for used chewing gum. One charming Year 4 pupil of mine did once leave the legend “F*** Mr Walpole”. As the master criminal in question had actually written “F*** Mr Wazpstt”, it didn’t take too long to identify him. It was a simple matter of looking up Individual Education Plan targets for that term (and noting the telltale red pen on the culprit’s forehead). Still, at least he could now tick the “ck” sound in his Jolly Phonics progress book.

Of course, arranging your classroom desks can be a political statement. Co-operative tables; formal rows; or the hippies’ compromise, the horseshoe shape? Every primary teacher has at least one anxiety dream about rearranging desks, where you wake up sweating and realise your life has reached a new low.

Many of us probably have happy memories of “proper” desks with lids, and inkwells for keeping pencil shavings and used tissues in. I still remember the foolish supply teacher who asked my class to “get back in their desks”. We happily obliged, smacking the lids repeatedly against ourselves in an effort to squeeze ourselves in, Houdini-style.

I must say I’m nonplussed by the new breed of super-desk, with pop-up computer screens hidden inside. These usually seem to be priced on the assumption that schools are only going to employ one teacher per 90 pupils. But of course that could never happen ...

I am still waiting for teachers’ chairs to be marketed with Bond villain accessories. Just think of the added incentive for pupils if they knew a wrong answer could lead to you flicking a switch and opening a shark pit underneath them.

Which teacher can honestly say they haven’t taught a pupil they dreamed of shooting out of an ejector seat? Forget more teaching assistants: the future of education is teachers in flying chairs hovering over rows of children, while Daleks patrol beneath. Well, come on, it makes more sense than Brain Gym.

More from Henry in a fortnight.