I liked the challenges posed by this puzzle: there were some really intriguing and clever bits for parsing.
I also like having Chambers and Brewers as ultimate verifying backstops. Each is a thoroughly lovely book in its own right, particularly Suzie Dent's brilliant edition of Brewers. The trouble is I keep on having to buy new editions as they come out; still, that gives something for people to get me for Xmas when I have no ideas.
Back to the puzzle. The P.O.R.G. at 5d. does not seem to fit with my answers for 16a (ending in P) and 24a (beginning with S). I am pretty sure of these two answers, but Ms Dent's Prince of Sleswig does not tally with either.