Thanks Hawk, glad I persevered with this one.
I enjoyed the clueing a lot and liked the very choice selection of words, particularly in the SE corner with 31d and 37a. The endgame was mercifully clear once I'd solved the two extra clues - although the first one was pretty tough without checking I thought.
Impressive construction overall and an enjoyable solve (a whole week's worth for me!). Thanks Hawk.