There are very many, many versions of this song of great antiquity. I know of English, Scottish and American versions. I have even heard the The King's Singers singing it on radio. The version I sing is taken from 80 English Folk Songs  collected by Cecil Sharp & Maud Karpeles during the years 1916 to 1918. I found this songbook in a second-hand bookshop in Auckland, New Zealand in 1994 and I suspect this proves something of immense importance.
Recently (October, 2013), I found another grim 11-verse variant given in Marrow Bones.

Lyrics