Walking through a London market a couple of young men passed, and they were going on about about "buying an eighth", and I realised they were talking about dope. And it occurred to me that that's one area where decimalisation is likely to run into the sand.

I mean, the basic measure might be a gram rather than an ounce, but, as I understand it, the custom isn't to go in for trying to divide it by ten, but into more sensible fractions, like halves and quarters and eighths, that can be obtained by dividing in two.