I’m puzzled. What is missing about the Druids?
The Romans beat the ‘English’, got in to southern Scotland.
They took much of Wales in a very brutal fashion. They took the heartland of the druids, the Holy Isle ... but they didn’t take Ireland or even all of Wales. They left Alba (the Picts) pretty much untouched.
We were left with the Bardic tradition. In Ireland we had the complete tradition. We are after all ... Celtic.
Three divides of bards. A means to have a functioning society with rights to land, a right to law, a right to justice and poetry of the soul. Sounds a bit like the USA.
ACelt. Alba go Bragh.