Right Graham, I'll cover processing of Mono converion & leave others to comment on overall photograph composition, subject, exposure etc....
Well the only way to comment on processing is to try it yourself & I have to say overall I couldn't better what you have done with the normal processes I use...so well done
The only area I notice on yours that needs improvement is the blown highlights, especially on the building top right & roof of middle building at right of picture.
Found the follwing whilst prcoessing shot:-
Trying to convert using RED channel mixer caused an almost IR effect on trees, but the sea & sky were good. For the trees in foreground the best mix was around 40% green & 60% blue in CMixer....all trial & error. So a 2 layer conversion would be needed in my process, with layer mask to bring shot together. With the buildings being so small in the shot, there was no real detail to enhance by USM. The sky did show pixelation / noise though during conversion, which I notice your has too.
Overall I would say you chose a hard shot to convert to Mono, but from what I have tried, you have got the most from the shot without spending considerable time playing in PS with lots of layers & tweaks