Great Photos. I remember going to a talk by the photographer at Penrhyn camera club about how he took them. His name escapes me at the moment.
Slightly misleading text accompanying the photos though. It was Cordite (low explosive) stored at Croesor and although it may suit present day expectations to say it was distributed across the UK, a significant 'lot' was burned over the hill behind Bronaber. It wiped out the fish within Afon Cain from the location downstream for many years with the area of land they used still bare today.