I had the delight of interviewing his son Eric a number of years ago when he was performing in in the Berkshires (USA---I have to remember that this is international).His father, Leon, has been seperated from his wife for many years and lives in the Vancouver area. He still does some performing there.
He was, indeed, quite popular during the "folk revival", but he also was quite popular in the more "musical" field.He has sung songs from the traditional to the pop. If you check out some old Vanguard and Decca recordings I think you will find some interesting things there.
His son is a wonderful performer on stage---gospel and blues are his forte.
If you can listen to his album called Needed Time. Just great.
Bill Hahn