Ah - Romeo an Juliet. Got a recording of that - its a great listen although the story line is very dated - remember Teddy Boys? Its not a 'folksong' per se, it is a Radio Ballad with dialogues and snatches of folk songs.
I wonder if they'll repeat the Radio Ballad 'The Iron Box' about life for blacks in US prisons.
Then there's the 6 ep. Radio Ballad series 'Off Limits' about the life of blacks in the US Army in the Vietnam War. The BBC never had the objectivity to actually air these. Only one ep. survives.
Then there is the pre-Parker/MacColl ballad opera 'The Man Who Went To War' starring Paul Robeson. This too was sponsored by the BBC. Recently it has just been rediscovered in the Library of Congress, but has been claimed by academia and is not likely to be released or aired for the public to hear.