Or do you mean that it is a traditional tale, and that Baring-Gould made it into a non-traditional song?

I think it more likely that Childe the Hunter is a traditional tale, the Childe of Plymstock - Childe was a mediaeval title for a young man who was a candidate for knighthood - rewritten first by Jonas Coaker of Postbridge and then again by Baring Gould, but set to a traditional tune.

The words were taken in a fragmentary form from Jonas Coaker, who "vastly preferred his own doggerel to what was traditional". However, the Notes on the Songs consider the tune to be "unquestionably an early harp tune, not later than the reign of Henry VII".