HCDS, and I have no idea why, but that's how it comes into my head. (If the Johnny Ball book you remember it from was "Second Thinks"[*], though, you could be on to something there.) It sounds like a skipping-rhyme, though, that way round. "Hearts, Clubs, Diamonds, Spades." "England, Ireland, Scotland, Wales." "Eggs, Bacon, Chips and Peas." You know. I wonder if it's something to do with the shapes of the vowels? I mean, that gives them that sing-song quality?

And as to the other question -- I like the idea, but I'd also like to see clothing prices shown as price per square whatever of fabric. That would show clearly what good value for money outerwear is as compared to underwear. I mean, a tshirt's going to be something like 2p per square inch, whereas a thong will be something more like £1 per square inch!

[*] Was there a First Thinks? Why did I only have the second?

Yes, there was a first book, called "Think Box". I have it, if you want to borrow it :-) But I'm afraid the HCDS thing was in it, and not in Second Thinks (I checked last night), so if you've only seen Second then you won't have seen the bit I'm thinking of.

I agree that HCDS has a nice swing to it, and I did idly wonder at one point whether that was something to do with it - but was foiled by the fact that I couldn't quite tell whether I only thought it had a nice swing because I was so used to using it as my default order.