Britannia Superior included
all England and Wales up to the Wirral - Wash line.
The northern frontier of Britannia Inferior was not stable untill the construction of the wall under Hadrian.
Britannia Inferior was divided into Flavia Caesarensis (which lay between a Wirral - Wash line and a Wirral - Humber line) and Britannia Secunda up to Hadrian's wall. Nothing definate is known about the provincial boundaries or the capitals other than the evidence of an inscription at Cirencester locating it in Brittania Prima.
Late sources add Valentia which seems to have been in the north and west possibly commanded from Carlisle.