I have solved all the clues except for 30 down which I cannot parse. I have the answer because I have a full grid, but I still cannot see it. Also stuck on the end-game because we are not told the size of the thing we are looking for. Seeing that Chambers actually gives an example of what we are looking for, it would be rather neat if that is the one, but there are some other (bigger) candidates. Hints appreciated.