Back to Robin Hood - modal analysis of Niles's "Robin Hood and the Potter":
Details behind the cut, but I think it's Hypodorian A, not C Major as Niles would have it.
Music given in key of C; no accidentals. Final is c. Seems open and shut case: C Major.
But the song does not sound like C Major.
Noticed: There are no F's in the whole thing. Is this a gapped scale? We could be in the key of G and never know it.
If we're in the key of G and the final is a c, we're in Lydian mode. Except that doesn't seem quite right either. So look closer.
The first notes of each measure are mostly c's and A's, with a few G's and an e.
The e is the highest note (and the lowest note, on the other side of things). Most of the notes are between G and c and c is easily the "most important note."
Let's assume we're really in the key of G.
For Hypodorian mode: the final would be A, the range would be E-e, and the tenor* would be c.
---The range and tenor are exactly right, but the final is wrong.
For Lydian mode: the final would be C, the range would be C-c, and the tenor would be G.
--- The final is right, but the range and tenor are wrong. G is placed as a transition/tension note, not the tenor.
For Hypolydian: the final would be c, the range would be G-g, and the tenor would be e.
--- The final is right, but the range and tenor are wrong. The e is only hit once in the melody; it is definitely not a tenor.
* As this isn't a chant, there isn't really a tenor, but there is a "most important note." Most of the measures start with c, which means most of the measures also lead to c. It's clearly the backbone of the piece.
Except for the final being wrong, this totally fits Hypodorian. Interestingly, the last melodic figure is an eighth-note on A that leads in to the final on C. I would consider ending on the A to "medievalify" the song; that last leap up to end on the tenor does sound more Appalachian to me. But I have no analysis of Appalachian music to support that. Perhaps it is worth looking into?
So my vote is "Hypodorian with a crazy final."