Challenging is the word, Geeker! I found this a real grind with hardly any straightforward clues. All fair enough in the end though, aside from 23A, which I've stared at for half an hour and still none the wiser, despite having the answer. Can anyone parse? (The only - extremely tenuous - solution that occurs to me is that function is a misprint and should be junction, but I'm really clutching at straws there!)