I liked John Moulden's attempt to inject a little academic rigour into this discussion but I suspect that if John himself, with his wealth of knowledge, hasn't been able to trace much on the roots of Celtic music in the American tradition, it isn't going to be traced. Not that it isn't there, I suppose there must be, but there doesn't seem to be a paper trail.

Even when there are tunes in common (and there doesn't seem to be all that many) the styles of playing would appear to be pretty different. I recall a bluegrass fiddler playing "Hop High Ladies" with a fiddler steeped in the Irish tradition playing "Miss McLeod's Reel" (yes, I know it's a Scots tune). The bluegrass fiddler, trying to show the Irish one how to get the American sound, would urge him, "Play less, play less".

There is, of course, no shortage of the apocryphal and speculation. About ten years ago I heard it suggested that the unpleasant term "hillbilly" came from the fact that so many of the poor whites in the Appalachian region came from Ulster protestant stock. Their love of King William (Billy) of Orange gave rise to the epithet. I have lately heard this repeated by sensible people as an undisputed fact. I don't believe a word of it, but I'm willing to be proved wrong.

Possibly a more useful avenue of exploration would be the influence of the American tradition on the folk music this side of the Atlantic.