Two questions to finish it off:
If 24d is Landseer, what is the connection with Moore?
Is the word we are supposed to invent a new clue for the name of the author beginning with B minus the last letter?
Would be grateful for any explanations!
Landseer was a sculptor as well as a painter (he did the lions in Trafalgar Square), and that's the link in Theme word D. You're right about the word to be clued.
Pogle2 - do you want the answers to 8ac, 42ac & 32dn, or just the link? The link is that 8ac and 32dn can both follow 42ac to give alternative names (one 2-word, one hyphenated) of fishes. They were new to me, but verifiable in Chambers.