Thank you Imogen for a really brilliant crossword. The clues were so clever and witty. Thanks also to those of you who gave hints and tips.I surprised myself by getting the Tennyson clue really quickly and can remember studying that particular poem for O Level English a very long time ago.
I initially took the defn. of 21 to be the first 2 words of the clue. But it seems to be an &lit (something that often escapes me). Either the first 4 and/or final 4 words of the clue would be a more accurate definition.