George H: Once shorn of its hairiness, your root question is a fair one deserving of a fair answer. I use the term "Celtic Isles" to denote an area where Celtic culture once prevailed and is yet either prevalent or prominent. I believe it is a more apt descriptor than the common geo-political one, particularly when seeking to understand the commonalities of folk traditions within the area. I understand the term to be independant of geo-political concerns, although I can understand how some might feel compelled to read more into it.

Apologies to all for going a bit beyond the pale.