No identification made yet.
No interactions present.
It could be Rhizocarpon petraeum but thats not a definite ID.
Crustose lichens can be hard/impossible to identify in the field, let alone from photo's! They really need testing for the K and C reactions, and details of whether they were on an acidic or basic substrate are very important too.
Lat/Lng: 52.2, -3.4
OS grid ref: SO0560