Crustose lichen, substrate granite, southfacing, grey
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.
It's not Ochrolechia parella as the apothecia (fruiting bodies) are the wrong colour.
If you compare your photo with the photo's of O. parella in the link below you'll see the difference:
Lat/Lng: 50.4, -4.1
OS grid ref: SX5567