Thanks, Dhope: parsing of 20a was baffling me too! Very clever clue, perhaps COD.
FOI was unfotunatelt a wrong answer to 2d: I carelessly invented and verified a word which wasn't quite an anagram, but realised it had to be wrong when I solved 7 and 9 but they didn't fit!
Used a few nudges from you kind people to get near to completion.
Still stuck on NE corner: not sure of my 8, and nothing for 5, 6, 10. Hints, please?