White paint-like appearance on Elder.
Caution: Do NOT use iSpot to identify fungi to eat!
Some fungi are very poisonous so a mistaken ID could have serious consequences.
No interactions present.
I have not had any response so far and have no idea how many similar species there may be.
I have seen something similar on other trees too. According to Roger Phillips' book, this species occurs on "deciduous wood, especially Elder" so yours might easily be the same species.
Lat/Lng: 51.3701, 0.0146
OS grid ref: TQ403653