It is growing on the trunk of a mature Italian Alder.
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.
Thanks again, this was such a strikingly bright green and there were more similar ones around the trunk I continued looking on the internet and in Dobson trying to key out for a Green specimen.
So colour is yet another complication to look out for in identifying lichen!
Wildlife of Assynt
You can check ones like that for the K+ crimson reaction.
I've come to the conclusion that pretty much everything is variable with lichens!
Lat/Lng: 50.8, -0.3
OS grid ref: TQ2506