To be perfectly honest with you, Percy's Reliques is the more likely having been much more accessible since it first appeared in the middle of the 18thc. It has gone through many editions, some very cheap ones like Everyman. And then of course there are all the other publications that dipped into it, including Child himself of course, particularly in E&SB in the 1860s.

Not a Child Ballad as such but may be of interest. The Bramble Briar/Bruton Town/Murdered Servantman Roud 18, Laws M32, only exists in fairly brief versions in British oral tradition, yet on your side of the pond there are 2 early versions from Mss more than twice as long as the longest British version. They both give the merchant as from Bridg(e)water which isn't far from Bruton. I presume these longer versions are pretty close to the original stall copy. At one point I was beginning to think that the ballad may have been American originally as there are many Bridgewaters in the Eastern States. I have since changed my mind having seen a Bristol printed garland ballad with similar wording. I would dearly like to find the orginal ballad.