Now that I've read some of the comments by Brian and Steve I'd like to make an observation.

As mentioned earlier in this thread The Lord Thomas broadside was supposed to be the source of the English version of the ballad both in the British Isles and in North America. However stanza 4 of the broadside never showed up in traditional versions- therefore the versions were all from tradition and the broadside was written from tradition but the printer added stanza 4. This is provable.

I'm coming to the opinion that rather than saying "it takes very little time for a ballad to get into oral tradition from print," we should be saying, "the ballad was taken from tradition and captured in print at that moment in time."

Also that "both the traditional (ur-ballad) and the print version helped disseminate the ballad." And that "broadside printers changed and elaborated the ballad text."

The Roxburghe ballad of 1720-1750, in my opinion, sounds like it has been "created from tradition." It does not seem like it comes from the lips of the masses. I'm not doubting that some of it could be based on the events of 1726 as Fowler proposes. I just don't think this is necessarily a historical ballad- obviously Charles Stewart never met Polly's ghost - but I believe it is based on a murder in that area (because of the attached place names)- possibly at that time or earlier.

Richie