Sarbs26, both are unusual words. Your second choice is correct in each case.
19 Def. is 'all' (1'5), in Chambers as 'everything'. 1-letter abbreviation + an anagram.
20 Def. is 'Will's complaining' A word for 'purpose' minus A
I'm with Sattrom on this one - many thanks, Saarbs26. Spectator 2760 is by far the hardest crossword I've encountered from the Spectator thus far, and 19/20 had held me up for a full week. Finished now, though. Phew!