Many thanks for the help with this - never cease to be amazed at the open-handed generosity of this forum - the true spirit of passing on what you have that brought me into folk song.
Thanks too to Jo for making this article available to all - I couldn't believe that it was so difficult to find.
As far as the index of ballad books, I suggest that you keep them as straightforward photoscans rather than attempting to read them as word documents - quite a few are in other alphabets that won't transpose into English.
Best
Jim Carroll