Xanthoria elegans (Link) Th. Fr.
Foliose, with yellow to deep orange, very narrow, adpressed, lobes. Apothecia concolorous with the thallus or more deeply coloured. On nutrient-enriched rocks, walls, concrete; widespread and locally common
Smith et al. editors (2009) The Lichens of Great Britain and Ireland
Dobson (2018) Lichens: an Illustrated Guide to the British and Irish Species