"I think the term "Celtic Music" smacks of marketing dept. speak and as such is meaningless."

Absolutely. I recently saw an American webpage which referred to Blowzabella as celtic music, which is ridiculous. It strikes me as being a marketing ploy aimed at Americans of Irish and Scottish ancestry.

I play hurdy-gurdy and often get asked "Is it celtic?" to which I reply firmly "no". I think because Irish folk music never died out and continues to flourish in England often more strongly than English folk music, non-folkies are often not really aware of any other folk tradition than the Irish one, and are unaware that drone-based music is common all over Europe and far beyond. They hear a drone and think "celtic".