"although specifically Celtic pagan elements are rare"

I would suggest the whole notion of Celtic paganism as a the defining influence on pre-Christian religion is a red herring anyway. Although it undoubtedly plays a part, I wonder if the ideas and concepts it introduced were simply absorbed into the indigenous culture similar to the way the Bon religion has been assimilated into Tibetan Buddhism.

George Ewart-Evans championed the idea that traces of our pre-Roman society remained in the folklore, customs and rituals of ordinary working rural people as a cohesive belief system up until the First World War when so many were slaughtered on the battlefields of Europe. The industrialisation of agriculture led to the demise of working horse teams, the change in agricultural practices and the subsequent loss of beliefs and customs that went with them. When we lost this continuity, we lost a "cast of mind" (to quote Ewart-Evans) that provided a context for the old magic and lore to exist in. Perhaps that is why we struggle to see the truth of Green Men and foliate heads; we need to be looking back at a our old folklore to gain insight into these intriguing figures.

The Three Hares link was brilliant - how fascinating is that?