Stone inscriptions are the most important written source for 5th-7th century western-British history. Against a background for Old World prehistory and the classical civilizations, this book focuses on the inscribed memorial stones of Demetia and Dumnonia.

The author then traces a remarkable "venture to the interior" - the foundation of a small Dementian kingdom in the upper Usk valley, and examines documentary evidence for the first settler-king - Brychan - and, as monk and saint, his connection with Lundy Island (in the Bristol Channel) and north Devon. Evidence for a post-Roman native kingdom in Cornwall, Devon and part of Somerset is next considered, as is minor Irish settlement in west Cornwall around the year 400, and an isolated introduction of Christianity from 5th-century Gaul. Inscribed stones show that the conversion of Dumnonia to Christianity - though field-work has revealed that, far from being a Land of Saints, the deep south-west did not become Christian until well into the 6th century.