"I'm not denigrating head voice - extremely attractive when used well (and sparingly), but it raises problems which have to be noticed and need to be dealt with."
what are these problems and on whose authority to they have to be dealt with.
As far as I can hear Shirley is using her natural voice rather similiar to her speaking voice, she is from Sussex and speaks with a slight Sussex accent. In my experience all Traditional singers do this,and most of them know nothing about chest voices or head voices
the terms head voice and chest voice appear to have first surfaced sometime in the uk folk revival in the seventies, and seem to be connected with the Critics group.
So Lloyd said "bucolic being fairly rare in folk song" are we suposed to take this statement without a challenge,   here is harry cox singing with a rural accent.http://www.youtube.com/watch?v=YsxG06FMA-Y Walter Pardon also sang in a norfolk bucolic accent, dictionary definition of bucolic [rustic, pastoral, of the countryside]