Dave, Just in case no one else answers, though that is unlikely, there may be two options that I can think of. 1. Glyn Tarrell - this runs southwest from Brecon to Storey Arms, its basically the route of the A470 and runs through Libanus 2. Glyn Tawe - a misprint - this is the upper Swansea valley north east of Ystradgynlais. There may be more options Regards Roger M. Evans