No identification made yet.
No interactions present.
Either a Lecidea or one of its several related genera. Best not to think deeply about these until one has data on microscopic characters.
There is a kind of Murphy's Law operating here - anytime one takes a good photograph of one of these, the apothecia prove to be immature and vital microscopic characters are unavailable. Or maybe it just applies to me.
Lat/Lng: 50.4939, -3.943
OS grid ref: SX622678