Mick:

Thanks for transcribing the Quinn tune. There are however several errors in that abc of Coates.

When I said "the first three notes" I should have said the initial progression from lower dominant to tonic (i.e. D to G in the key of G). In the Coates abc the first note of the main tune is given incorrectly as a high D.

Richie:
"To me it was instantly clear that the Coates and Quinn are the same after looking at the Coates melody."

I don't see how you can say they are 'the same'. There are similarities (at least partly arising from the textual pattern) but the contours are different.

The Gentry version also has a similar text format, and the leap to high G on 'stood' does recall Coates. Again there are substantial differences to the Quinn tune contour.

There's not a tradition in England but theses should be separate.

There may be a typo here, but we know of two variants from England, both listed on your site. How is this "not a tradition"? There is relatively little evidence for English balladry in the late 18th / early 19th century, but the existence of those two at least suggests some previous history.

"We don't know if Mrs. Coates nee Allen learned it from her family or her husband's so its conjecture"

Exactly - so you need to be careful about using it to support a link with Ireland.