Your average aeroplane toilet is not a space of luxury. The size of a largish cupboard, lit to throw no shadows like a morgue, it presents several structural disincentives to actual use.

However, one does occasionally need to use the toilet. I walk up the aisle, dodging people leaning out of their seats to avoid their neighbours, dreading the sight that is inevitably to greet me.

I half-open the door, look in and see exactly what I expect, almost every time. Why do people, on being faced with a seat in a public toilet, feel the need to pee on it And even worse, why do they feel that some unknown omniscient being with pre-set duties is waiting to clean up after them Do these people always behave in this manner, or is it some special favour reserved for airline toilets In other words, do these people do the same thing at home

I doubt it, since there does seem to be an entrenched personal puritanism which extends to cleaning up after yourself. But it seems that given the choice, most of the worthies who crisscross the country collecting air miles wouldn&rsquot want to clean up at all. I&rsquom reasonably sure that the home imposes certain social restrictions on such mean-spirited behaviour. Since there are no nannies minding them in public spaces, an aeroplane toilet is considered fair game.

One of these days, I&rsquom going to take a red pen, and, in the fashion of the cutesy posters of my youth, I will write on the wall &ldquoIf you sprinkle, when you tinkle, please be sweet, and wipe the seat&rdquo, in a big horror movie font.

It&rsquos unlikely to have the slightest effect, and the airline will wipe it off, probably long before they clean the toilet seat. But it will make me feel a lot better.