Re @26-@30 inc.
Well, I certainly made this more difficult for myself than I needed to.
Following a post (See above) from the setter Odo/Rob, I was told that, even though I had successfully completed the puzzle, he suspected I had overlooked a particular part in relation to the theme. This was confirmed by Jono in a following post, relating to the first word. created by the extra letters.
Now, as it turns out, I had not made any mistakes at all - none. That said, I did wonder why the first word seemed so unrelated to the rest of those from the extra letters but, as one sometimes does, just shrugged my shoulders and presumed it was a bit in the theme work I'd missed.
But then (Jeez Bren, is this a post or a draft for a thriller you're trying to sell!) I noticed that if you change one of those extra letters it spells a name... one I definitely did recognise from the theme! Yes, I've since discovered it's spelt differently but it was too close not to be true so, change it I did - Yipee, I discovered the hidden gem 😀 Problem was though, that no matter how much verbal gymnastics I did and visits to Chambers I made, I couldn't get it to parse - obviously!
So I went back to my original and correct extra letter in the first word and thought about it some more, from different angles etc. and, lo and behold, the light finally dawned. Unfortunately, I wasn't at my computer so had to wait until I got home to check, but that made the confirmation all the more sweet.
Anyway, thank you again Odo/Rob, that finishing, theme related touch you managed to fit in has elevated this puzzle from the good to the brilliant.
(So, basically Bren, you were right, changed it, then changed it back and had a PDM - do you get paid by the word or something!!)