There is a set at Lesley Nelson's site: Joy Upon Thy Bright Cheek Dances (Hob Y Deri Dando)  Text and tune from William Cole's 1961 anthology; he points out that Hob Y Deri Dando means the pig under the oaks in Welsh.  He also states that the tune is related to Hai Down ir Deri Dando, and unfortunately adds, "which is an old song of the Druids"(!).  There is also a link to a set in Welsh (in Barry Taylor's Tunebook), with another English text which is not a translation of it.  There are quite a few websites which carry the two last texts, and midi; they appear all to have been lifted from Barry's site, mostly without acknowledgment.

A tune appeared in Davidson's Musical Miracles: Two Hundred Welsh Airs for a Shilling (1859, reprinted Llanerch, 1990s) as Hob Y Deri Dando: Away My Herd.  I recall singing a version (in English, of course) at school in the early 1960s; it would have been from a "Singing Together" pamphlet.  Unfortunately, it's not in any of those that I still have, and I don't now recall whether it was a form of the shanty or of one of the more genteel sets on which I presume the shanty was loosely based.