No identification made yet.
I'm just wondering if this has the same cause, Virus/Phytoplasma, as the unusual growth seen on a willow in your previous observation, http://www.ispot.org.uk/node/180666 . Both observations are in the same area and if its a virus/phytoplasma infection then it could be spread by a vector such as a leafhopper.
Out of interest does anyone have an opinion in which group, viruses and bacteria/phytoplasma should be placed.
Same occurred to me, of course. I meant to say that!
University of Edinburgh and Biodiversity Observatory (OU)
Lat/Lng: 52.015833333333, -0.70583333333333
OS grid ref: SP889360