I have been learning "The Unquiet Grave" using a melody I heard from a Joan Baez recording: https://www.youtube.com/watch?v=FOIAhXDqdPc

However, I just heard this version of the tune, apparently used on the show "Penny Dreadful": https://www.youtube.com/watch?v=1f-MTJ2MOR4.

I like the Penny Dreadful tune much better, as it seems to fit the mood of the song better. However, I would like to know where this tune comes from. Was it composed for the show, or is it a folk tune? (Basically, is it under copyright?)