Petraites is both right AND wrong. The Celtic religion was not Druidism. He's correct there......but I disagree with his assertion that the Druids were not in Britain.

I recently read a very interesting theory about the role of Druids in Celtic society. Sean B. Dunham in an article Caesar's perception of Gallic social structures puts forth the theory that we may have the role of the Druid all wrong. Whereas the modern view of them is that of priests, that in actuality they had the tripartite duties of priests, philosophers and judges. The ancient world didn't have the separation of church and state that we do now. Instead of being a mysterious magician priests, they actually were an oligarchical elite with both judicial and religious duties. The Brehons were the longest lasting branch of the Druidic teachings, lasting until the early 1600s when the Brehon Law in Ireland was replaced with English Common Law.


If so, it appears that Caesar had a much clearer picture of the Druids and the Celts than many have given him credit for. He understood the importance of the Druids which quite possibly accounts for his very harsh treatment of them. They held the history, the law, the wisdom, the religion of their society. Once this was removed, much of what made them Celts also eventually vanished.


source:

Celtic chiefdom, Celtic State, New Directions in Archaeology, Edited by Bettina Arnold and D. Blair Gibson, Cambridge University Press, 1996