Thanks everyone who for your contributions - it's been very enjoyable and interesting reading.
It's clear that some solvers can find particular clues easy while others might find the same ones difficult, and that's no bad thing.
Overall though, I think I was correct in my original assessment that this is one of the most difficult for a while. That's not a criticism, just more of an observation.
Also, judging from the lack of negative comments, I'd say it was enjoyed by all, so well done setter:-)