Overall this was much easier than usual for a Guardian prize, I found, but quite a few clues still took a fair bit of effort. FOI 21, which I saw as soon as I read the clue. LOI 14a, for which even after I knew what the answer had to be, I struggled for some time to work out why. Contenders for COD are 1a, 4d, 5a, 5d. I think I'll go for 5d. I am ashamed to say that it took me a couple of minutes to get 20d, which I should have got immediately, as the first half of it is something I've been stuck with all my life.