A magnificent puzzle - my favourite this year, I think, for some great clueing, tough but fair level, and such a clever end game.
One thing I’m slightly uneasy with is 19a. If I’m parsing it correctly, then ‘antique to’ should represent three letters. I can’t see anything concrete in the BRB that matches up for those particular letters being ‘to’ (the antique but is obvious). Any guidance on this, please? Also the ‘A duke…’ at the start seems slightly at odds with the usual rules of having no dust plus words or letters. Should it really just be ‘Duke…’? (unless there are two “Dukes” in the word and only one is missing?