I used to have this folkmusic encyclopaedia. In it was a fan letter from Peggy and Mike seeger when they were little kids to Earl Scruggs.

They were requesting Scruggs to play Fod, which is a bluegrass version of the old folksong Springfield mountain.

A few years later the purists were getting hot under the collar saying that Scruggs in particular, but bluegrass in general wasn't folk.

As the man on the door at The Grey Cock Folk Club said to me many years back - we've got to draw the line somewhere - meaning me as I'd said my main influence was Ralph McTell. I don't really know where the purist get off(apart from being ingratiating with folk legends) but they've said no to a hell of a lot of ordiary English folk, people who thought they had something to express.