 At this point Surrey was evidently under Kentish domination, as the abbey was founded under the patronage of King Ecgberht of Kent.However, a few years later at least part of it was subject to Mercia, since in 673–675 further lands were given to Chertsey Abbey by Frithuwald, a local sub-king () ruling under the sovereignty of Wulfhere of Mercia.A decade later Surrey passed into the hands of King Caedwalla of Wessex, who also conquered Kent and Sussex, and founded a monastery at Farnham in 686.