Well, I enjoyed that (but slow to post). The first prize over completed without resorting to this (wonderful!) forum for ages: 19A took me towards the theme and 17A locked it in for. I had to use a list on Wikipedia (promoting the mutual benefit bit of the web, rather than one of the tax free giants) to get all the themed answers but they're my time so I remembered most of them.
Nice to see words like 12A, 16D; lots of COD candidates but probably 8d