But I have found no indication that he or the Delmore Brothers ever secured a copyright on it.
That's significant because Scott "Skyland Scotty" Wiseman of N.C. (1909-1981) had recorded the same version (with a couple of minor differences and one more stanza) in 1934:
According to William Lightfoot, in "North Carolina Folklore" (1986), Wiseman had learned the song "in the mountains from an old folksinger named Aunt Nancy."
The bit about Darby and the minners appears in no field-collected version. Nor does the "Wasn't he a big 'un, boys" refrain.
Roud lists well over 200 appearances of "Darby's Ram/ The Derby Ram/ The Ram of Derbyshire."