In Brendan's absence, reluctantly starting a thread before going to bed...
Thanks to Picaroon for setting an absolute blinder! Finished it pretty quickly, but a delight all the way through. My running list of "good clues" / "COD candidates" had 16 (out of a possible 30)!
FOI 6. Co-LOI 19 and 27, which held me up longest and I saw at approximately the same time.
Embarrassment of riches in the COD department, but 25 is the clear winner. Too many other good ones to mention.
Not sure of parsing for 12, though I have a plausible solution.
Google was required to confirm solutions to 10 and 1a, though solutions clear from wordplay.
I'll rank the puzzle as slightly above the norm in difficulty, but enjoyment took priority.