A copy in the Bodleian Collection is dated between 1774 and 1825 (Harding B25(934), Angus, Printer.
Anoyther printing is dated 1816-....)

The last line in all copies- "Saying, "Here is fifty guineas....."

Charlie Byrd plays an instrumental, "Lay the Lily Low," which seems to have no relation to the tune wanted here.
http://www.youtube.com/watch?v=_omSOnfW9mk

Florence Reece sings a line or two of "Lay the Lily Low", Digital Library of Appalachia, but not identifiable as to any tune.
www.aca-dla.org

It is questionable as to whether the 'old hymn' (not seen) tune has anything in common with the tune used by Florence Reece for "Which Side Are You On."