Thanks to jono and barryc for parsing of 16d - I was completely at sea with that one! I actually don't think it's a very good clue - too convoluted.
I also found some of this more tricky than usual. Took ages to get 11a, even though it wasn't hard really. Would definitely have been helpful to have realised, or even thought about, the usual rhyming pair!
Wasn't happy with the definition for 17d; far too vague, but the cluing was fair.
I think 27a was my COD - so clever! 12d made me smile.