Jonathan,
The only sticking point for me is I'm pretty certain it's about 1750, probably one of those 3-4 column broadsheet pieces with about 20-odd verses produced by the likes of Dicey and Marshall, or a garland piece, probably printed in Bristol. Obviously as everyone knows it is taken directly from the Isabella story sans pot of basil. Therefore it obviously has many parallels on the continent, one of Child's pet criteria. I disagree with Belden who tried to link it to one or more of the German poetic versions. I think it's straight from the Decameron which had had many cheap reprints in English well before 1750.

Then again there are plenty of other pieces like this in Child (e.g., Keach i' the Creel) and plenty of dodgy pieces which Child even identified as such.