Sorry raggedy, and anyone else who tried my link at @18: the final full stop is not part of the link but this forum tool appears to have made it so. QXW is excellent and can be used to do much the same (and much more), but needs to be installed.
The 30d issue is interesting. The fact that something "in G" has one sharp (if we presume major is intended) is not attested in BRB, but then not everything needed for the clues is -- we are expected to find out for ourselves what cities there are in Cambridgeshire (for 10d), or what country Riga is in (for 36a), etc, so I guess the question really is what degree of non-BRB general knowledge is acceptable to require as part of solving a clue. Geographic and political knowledge appears to be normal, musical theory not so much.
There was some delightful clueing in this one, though one or two were a bit of a stretch for me. I'm still laughing at 36a. I was not a fan of the GWIT-fest ending, ingenious though it is and entirely clear once spotted. For anyone still struggling, dodgepot@53 is worth reading very carefully indeed. I'm afraid I can also never really like any puzzle that requires me to rub out most of my hard work. We haven't had one of these for a while. For me, every letter entered is painful, so every letter rubbed out is equally so...!