PD I'd say. There are more versions. It is Roud 1048. Go to EFDSS website VWML and into their catalogue of songs. Scroll down to Roud numbers and enter 1048. That will give you all the versions, at least 3.
I wouldn't worry about copyright. The source is well out of copyright and the song is easily demonstrated PD traditional, but go back to one of the sources just to be on the safe side.