Onwards from Coccium…

From the Domesday book…

I. As to the history of the territory. Whilst our heathen
English forefathers were gradually lirst devastating, and then
themselves settling down in, the eastern and southern parts of
the country, to which they gave their name, the British principalities
in the north-west drew together into the kingdom of
Strathclyde a kingdom which stretched from the Clyde to the
Mersey, and from the sea to the hills that form the watershed.
The capital of this kingdom was Alclwyd, or Dumbarton, which
was strongly fortified to protect the British from the incursions of
the Scots and Picts of the north ; the hills guarded them on the
east from the Northumbrian English and the Britons of Elmet
(which, roughly speaking, answered to the West Riding); south
of the Mersey was another British kingdom, Gwynedd, of which
the capital was Chester. It was not until the seventh century
that the southern portion of the kingdom of Strathclyde, that
part which now forms the county of Lancaster, became English
territory ; it was gradually dismembered by the Northumbrian
English.