 Archaeology suggests that it came to Roman Britain slowly, gaining adherents among coastal merchants and in the upper classes first, and never becoming widespread outside of the southeast in the Roman Era.There is also evidence of a preference for non-Christian devotion in parts of Britain, such as in the upper regions of the Severn Estuary in the 4th century, from the Forest of Dean east of the River Wye continuously around the coast of the estuary, up to and including Somerset.In the "De Excidio et Conquestu Britanniae", written c. 540, Gildas provides a story of the martyrdom of Saint Alban at Verulamium, and of Julius and Aaron at "Legionum Urbis", the 'City of the Legion', saying that this occurred during a persecution of Christians at a time when 'decrees' against them were issued.