Started an hour ago and not read all the clues yet, but finding it difficult (perhaps I should give up the prize puzzle as it takes too much of my time on Saturday). Thanks for the hint on 21ac. Why didn't I see that as I read through. Perhaps I can build on it.
I'm desperately trying to remember what Thor Heyerdahl was famous for. So far, I've come up with the Kontiki expedition and Easter Island, so haven't made the connection yet. And what should I make of Kant? or Wordsworth?
I'll read the rest of the clues and be back later.