I examined three Wild Service Trees near Cowfold. All three had the same lichen community growing on them.
Habitat: Low Weald ancient woodlands on clay. Ancient woodland status suggested through presence of Yellow Archangel, Bluebells, Wood Sedge, Midland Hawthorn, and Wild Service Trees
This map showing the location of these tress is from Dave Bang's The Land of the Brighton Line: A field guide to the Middle Sussex and South East Surrey Weald (2018)
Lichens:
Possibly Buellia griseovirens
Lepra amara Bitter Wart Lichen
Flavoparmelia caperata Common Greenshield Lichen
Lecidella elaeochroma Lecidella Lichen
Pyrrhospora quernea
Possibly Punctelia jeckeri Powdered Speckled Shield Lichen
Hypotrachyna afrorevoluta
Mosses:
Hypnum cupressiforme Cypress-leaved Plait-Moss
Liverworts:
Frullania dilatata Dilated Scalewort
Metzgeria furcata Forked Veilwort
Significant organisms near the tree:
Crataegus laevigata Midland Hawthorn
Hyacinthoides non-scripta Bluebell