Cryptic crossword No 3,550

Got 1a as my first in, leading to a satisfying start. Threw in 5d based on definition and half the wordplay. Lovely surfaces on 15a and 23a. Amazed at 27a - so neat! Some fun novel techniques in 10a and 19a, though 17d and 24d were a little mean in my books ;) I got 20d before 25a so that was a fun reversal. I'll admit to DNF'ing on a couple clues though; in particular the deletion in 11a was over my head, and 4d and 14d went in just on the crossing letters - though they're fair, just hard!