The link above to Ewan himself writing about the making of the ballads, originally featured on Peggy's website, is no longer in service. I find that commonly, and is the single greatest drawback to things being hosted on personal websites which will almost always disappear at some point. Anyway, for future seekers, hopefully the Wayback Machine will still exist when you arrive:

https://web.archive.org/web/20060711032854/http://www.pegseeger.com/html/radioballads.html

For that matter, I hope something is planned for preserving Mudcat in a similar manner. I haven't checked to see if it's in the Wayback Machine.