There is a difference between the way scholars and researchers think of music and the way sellers/purchasers think of it. One is interested in the 'real' origin, no matter how unlikely or obscure, the other simply ease of access. This can give rise to some odd classifications. To find English Traditional Folk on "Emusic" for example, you look under "World/Reggae" and then the subsection "Celtic/British Isles"

I can just picture Bob Copper in dreadlocks!