During the Bioblitz Simon Moore drew my attention to some bracket fungi five feet or so up a tree. The fruitbody looked like Phellinus igniarius (Willow bracket) except this was not a willow but a poplar!! I recalled something about a phellinus specific to poplar. The tree I am now led to believe is the Grey Poplar.
After discussion with Alan Lucas the possibility that this is Phellinus populicola, a species with only very few UK records from Bucks and Surrey, continued as a possibility. Subsequently this has been reviewed at Kew and is now an accepted record.