Well, as to Derby or Darby, neither is correct for the oldest version of the song. It's "The Tup of Dirram" (Durham). More if I can find a certain reference book I'm supposed to have someplace. I've got to find who and where published the history of the Derby Ram that Joe Hickerson mentioned to me once. "Tript of Dirram" in the Straloch Lute MS, 1627, was probably the tune, but the MS has been missing for about 150 years, and that's not one that G. F. Graham copied from the MS (See Scots tune MS file on my website)['tript' in English is a just a variant of 'tripe'. Maybe Abby or someone can come up with the meaning in Scots.]