Thanks to Picaroon, who's rising to the very top of my setter pantheon, on a brilliant, though extremely challenging Prize!
So many outstanding clues (my short list numbered 19!) that it's almost impossible to specify one. Let's call 1d and 27 co-winners. Difficult to recall a puzzle with such a high level of cluing.
FOI 24: almost the entire first pass resulted in blanks. For about a half-hour I despaired of being able to complete even a third of the grid.
LOI 27, clever misdirection held me up.
Can't see a theme, though I rarely do and am too tired at this point. Found three pairs of somewhat related clues, but nothing comprehensive. Four entries reflected Picaroon's Pauline side. :-) Only needed Google for one clue, a commercial trademark (?).
Good luck to forum solvers, there should be an active dialogue this weekend.