Opegrapha gyrocarpa

Orange brown mosaic with black edges (like map lichen); "growing on vertical and slightly shaded base poor rocks surfaces: 

Learn your Lichens Series 1. Arthonia radiata 2. Caloplaca flavovirescens 3. Acrocordia conoidea 4. Squamarina cartilaginea 5. Xanthoria parietina 6. Lecanora gangaleoides 7. Physcia tenella 8. Lepraria incana 9. Porpidia tuberculosa 10. Psilolechia lucida 11. Lecanora soralifera  12. Opegrapha gyrocarpa

See this video of the tomb to the let of the block tomb marked with the arrow. eventually the video shows the block tomb stone with its Opegrapha gyrocarpa on the shaded vertical parts of the tomb

http://www.naturespot.org.uk/species/opegrapha-gyrocarpa