There are theories that some of the pre Roman inhabitants of these isles were atlanteans. Skilled sea traders inhabiting North western Africa, Iberia and the western parts of Europe. Many people have tried to find links to people like the Tuareg/Burbers and the early Celts using linguistics, but I don’t think anything convincing has ever been established.
Many of the early Welsh saints are often portrayed as being White, but that may not have been the case - in fact it most probably wasn’t the case. It is certainly the case that many of the earlier christian saints were not - Meuricanius or St Maurice/St Moritz for example (Meurig?).
There is room for our established perceptions and portrayals of history to perhaps consider some of these things.