Page "Cerdic of Wessex" Paragraph 14

It is thus possible ... to think of Cerdic as the head of a partly British noble family with extensive territorial interests at the western end of the Litus Saxonicum.

As such he may well have been entrusted in the last days of Roman, or sub-Roman authority with its defence.

He would then be what in later Anglo-Saxon terminology could be described as an ealdorman.

...

If such a dominant native family as that of Cerdic had already developed blood-relationships with existing Saxon and Jutish settlers at this end of the Saxon Shore, it could very well be tempted, once effective Roman authority had faded, to go further.

It might have taken matters into its own hands and after eliminating any surviving pockets of resistance by competing British chieftains, such as the mysterious Natanleod of annal 508, it could ' begin to reign ' without recognizing in future any superior authority.