Minor British Institutions: The cat flap

The cat flap, besides being especially popular in Britain, has claims to be our invention; by Isaac Newton, no less, who cut a hole in the door to his Cambridge rooms to allow his cat to come and go without interrupting the Newtonian cogitations. He then cut a smaller hole for its kittens.

Some doubt the story, but there was clearly something about motion going on, and later reports of two stopped-up holes in the door, since lost.

Whatever, cat flaps have long provided ease for both owner and pet, whichever they are. Recently, this has been marred by robbers using the flap to reach up for door keys, and even to crawl through.

This is the more remarkable given research showing that half our cats will be too fat to fit through the standard flap in 10 years. The joke – "How do you make a cat flap?" "Put it in a wheelie bin" – is not thought particularly funny, or clever.