Thanks Mattrom and thanks also to Noctifer. That was quite a work out! The parsing of some clues is really quite tricky, which I think is partly because of the two different ways in which across and down clues are constructed, but I think I have got there in the end. The preamble says one answer is an abbreviation, but I think there are two. I enjoyed this puzzle a lot (even though the theme has never been of interest to me}.