For a value of 'Celt'. The 'traditional' Celtic migration theory starts with Spain. But genetic connection and cultural identity are not the same -- cultures and languages mutate, drift, intermix and change over time and genetic links are far enough back that in terms of recorded culture, they aren't hugely helpful. Interesting, though.
I was delighted with the Church of Wales' decision to elect female bishops. They didn't have them in the early middle ages, not at all.
I have a soft spot for some of the Welsh saints. Interesting set of Lives.