American Folkie/anon guest, You say, "This thread shows just how deep and virulent the nationalist sentiments run among many English traditional folk."
Is that really what you believe, or are you being provocative? I think that this thread shows that a lot of people are somewhat clear on their ancient history (me included), not that lots of us who are interested in English traditional music are making unpleasant value judgements about people from areas of the Europe commonly refered to as Celtic.
The comments about different DNA strains and concrentrations in particular areas suggest an interest in human history, not necessarily a prejudice about "other" people.
Jane