Leprocaulon calcicola is described as new from walls in SE England; it is leprose, pale to mid blue-grey, and contains zeorin and usnic acid. It differs from L. knudsenii from North America in its habitat on mortared walls rather than non-calcareous rock and in its ITS sequence. ‘Lecanora’ ecorticata differs in the yellower colour, and the presence of unidentified fatty acids and traces of unknown terpenoids (but not zeorin) by thin-layer chromatography. Leprose lichens with usnic acid are still poorly known and sequencing must be used to support morphological and chemical studies.