@williamseal - reading your post made me realise I hadn’t got round to joining the “relevant cells”. This has revealed another nice touch to the puzzle that I’d missed until now.
You mention the clashes don’t lead to names you recognise - they won’t, they are just two letters which are probably meaningless until you have the theme.
FWIW, my way in to the theme was the campaigner’s name which was quite easy to spot.