The transformation of Roman Britain

[Agraes]

Its a bit more clear now :wink:

One place that had its original Celtic language completely erased was Cumbria (Cumbrian being another Brythonic language). But apparently there might be evidence of placenames containing Cumbrian remaining around Wigan showing the locals there continued using it for a long time.

At least Carlisle!

I don't think lot of germanic people settled down in Rheged/Cumbria after its conquest by the Northumbrian. There was also irish colonies on the coast, and the Brythonic kingdom of Strathclyde (united with Scotland in the XIth century) controlled the area sometimes. As I know, there was also strong norse influence here. Well, under the weight of Gaelic, Norse and Germanic influences, the Brythonic population of Northern England/Southern Scotland probably lost their language in the high middle ages, while their once brythonic elite (Urien Rheged, Gwalchmai of Gododdin, even perhaps Arthur for some scholars) was gone since centuries.

Another case is Wessex and Dumnonia. Wessex rose in power in the area very near of Dumnonia, the ancient tribal territory of the Belgae. It has been suggested that Cerdic was a foederati leader of mixed birth. His firth success may be explained by a population used to live near those germanic foederati and supporting them. And when the time of conquest rise, they feel more Saxons than Britons, thus supporting their germanic leader against the Wealas - the Dumnonians.

Foederati often appeared to take advantage of the situation. Ida of Bernicia chased the Bryneich king from his palace, and Bryneich only remained as an enclave. Deirans will take control of Ebrauc, the mighty kingdom of Peredur ap Ellifer Gosgordfawr.

And when it cames to choose your identidy as a Briton or a Saxon, when you would be given some law advantages by adopting germanic customs, religion and language, Britons would have choose this - at least part of them. A parallel may be Muslim Spain, when Christians paid more imposition than Muslims.