I'm with Jim.
What a load of bollocks about Scarborough! Like most broadside ballads the place name gets shifted about willy nilly and can be almost anywhere at whim. As for medieval very few of the Child ballads were around in that era. Despite what Child's preferences were many of these originated on broadsides and few can be traced back any further than the 16th century. Some of them may have been around as folk tales and later fashioned into ballads.
I wouldn't put much faith in some of the above Scottish versions either. Most of those were rehashed by literary men and antiquarians.
(That should put the cat among the pigeons, Jim)