Brendan,
16 was also my COD. Thought 23, 1d, 20, 20, 23 and 9 were good as well. Didn't notice a theme either. FOI 2. LOI 14, not because it was hard but I simply skipped over it; thought the grid was complete but review showed two empty boxes. 😀
Thanks to Everyman, good puzzle, I didn't like it quite as much as last week's, but that one was exceptional. A bit harder than the norm, perhaps.
Hints to get started: two long across anagrams, plus hiddens in both across and down.
Only quibble is 19, which doesn't seem very cryptic, but I'm likely missing something.