There seems to be some debate, but I hold with those who say that Romanization was never extremely strong in Britain to begin with outside of the southeast coast. After all, it took 3 legions to keep the place pacified, and few if any Britons made it to the Senatorial order. So perhaps what we're dealing with is a thin coating of Romanization that quickly wore off with the arrival of the Saxons, while Romanization on the Continent was much more embedded.