In the Poetical Works of Sir Walter Scott Bart, vol IV Minstrelsy of the Scottish Border, Part Third, Imitations of the Ancient Ballad, the last paragraph of the introduction to Christie's Will says
"The reader is not to regard the ballad as of genuine and unmixed antiquity, though some stanzas are current upon the Border, in a corrupted state. They have been eked and joined together, in the rude and ludicrous manner of the original; but as it must be considered as, on the whole, a modern ballad, it is transferred to this department of the work."   
The next ballad is Thomas the Rhymer and that has a tune arranged for 'piano forte' but there is no tune printed for Christie's Will.

Robyn