This 3-part jig is transcribed from Zoe Conway’s debut CD, with the composer listed as "traditional". It seems quite different from a two-part version previously posted except for having the same A part. No idea which is "correct"….but I really like this version. The harmony is just the simplest possible; the tune could be harmonized in a great many interesting ways. BTW I did a little research on so-called "heavy" (or treble) jigs, but it’s still not clear to me what makes a tune a "heavy jig" (and thus why this tune is one….or is not!). The term seems to originate from a style of dance. So to be a "heavy jig", does a tune have to be one intended to be danced to in that style?
Partial answer to my own question: a "heavy jig" is one danced to in "heavy" shoes, those big thick-soled clumpy-looking numbers that make such a satisfying ker-THUMP when one (who is competent) dances in them. I still wonder what qualifies a jig as "heavy", i.e. whether it is a type of set-dance, with dance and tune paired….?