Now, setting a booby-trap for a respectable citizen like a head master (even of an inferior school to your own) is not a matter to be approached lightly and without careful preparation. I don’t suppose I’ve ever selected a lunch with more thought than I did that day. And after a nicely-balanced meal, preceded by a couple of dry Martinis, washed down with a half bot. of a nice light, dry champagne, and followed by a spot of brandy, I could have set a booby-trap for a bishop.

The only really difficult part of the campaign was to get rid of the office-boy; for naturally you don’t want witnesses when you’re shoving bags of flour on doors. Fortunately, every man has his price, and it wasn’t long before I contrived to persuade the lad that there was sickness at home and he was needed at Cricklewood. This done, I mounted a chair and got to work.