Galicia revisited

Some weeks ago I asked why some vestiges of Celtic culture had
survived in the north west of the Iberian peninsular, while it had
apparently died out elsewhere.
When the Saxons pressed westwards into south western Britain there
was a migration across the English Channel to what is now Britanny.
Is there any evidence that migrants also settled in north west Spain
from Britain, and could this have reinforced Celtic culture there?
Regards
David James