Shiny grey-green thallus, narrow divided branches with up-turned edges forming a single deep channel. Apothecia at or near the branch tips. More common in the west and often coastal. Grows on basic bark and twigs

References: 
Smith, C.W. et al. editors (2009) The Lichens of Great Britain and Irelandd
Dobson, F.S. (2018) Lichens: an Illustrated Guide to the British and Irish Species