The lichen colonization of recently created urban wasteland is described by reference to 40 sites in England, Scotland and Wales. The 100 species encountered form a series of overlapping communities in which successional relationships over the first 16 years have been investigated. Floristic variation within towns tends to be greater than variation between them. On a national scale climatological, geological and historical factors appear to play only a small part in determining the composition of this pioneering flora. Many species can be accommodated within the strategy group stress-tolerant ruderals; a few possess the character of ruderals. The heyday of this component of the urban flora may be drawing to a close. Acarospora heppii f. luteopruinosa, Lecidea polycarpella and Micarea excipulata are reported as new to Britain.