This is great.

"...my charmer, she's the daughter of a farmer" is a line I've heard my student say at least once but what I mentioned in the initial post was his most consistent repeated recollection.

Perhaps my student is remembering "my lady blue and white"? (With my lady blue(by?) and by (I?))
which would tie in with what the BBC notes for Lal Smith's rendition say. Although the folktrax recording doesn't have mention of colours.

All fascinating stuff, my student will be delighted with this.