OK, Guy, of the current younger crop of British female folk singers, I would recommend:

Nancy Wallace

http://www.youtube.com/watch?v=Eg5RZ6PJ8bk
(though there is some unfortunate audience action!!)

Bella Hardy
http://www.youtube.com/watch?v=JpNUHgEYB2Q&feature=related

Ruth Notman
http://www.youtube.com/watch?v=hz5bjXq8-z4&feature=related

These aren't the greatest quality recordings but you should get an idea of how they sound.