I agree with Anglo (why are you modest? Are you Somebody I probably have heard of?) that the Roberts/Barrand version sounds more like the folk process, or memory at work, than a deliberate attempt to make it sound more "folky". I first heard them do this in 1976 in the Hanover, NH Christmas Revels. I loved it then and love it now. But I don't teach it at my school- these kids are too damn sophisticated and getting them to sing "rise up jock" without a smirk or worse would be more than I would care to attempt.