Thanks for the time and enthusiasm Martin. I see what you mean, as despite it's superficially distinctive appearance I rapidly came to the conclusion that I wasn't up to id'ing this ...
There are mature Beech on the eastern side of the pond, Scots Pine + heather slope to the west, Oak to the north and Hazel, Birch, etc amongst the moss mats in the wetter southern part (where it's fed from). Quite an interesting mix for West Berks.
Unfortunately, it's one of those occasions when I fluffed the only close shot, see below (it flew off after that). I'll check the flight period for the suggested candidate and see if I can get something better next time.
Many thanks,
Darren.