Despite the name, this is a reel and not a jig. It is closely related to The Kelfenora Jig (which actually is a jig) and a number of other tunes. Jigs were originally tunes sung after a play by the clowns. The word 'jig' applied to a form of rhyme and is of uncertain derivation.
Ref: https://thesession.org/tunes/779
Ref: https://tunearch.org/wiki/Annotation:Chorus_Jig_(1)
: | D | D | D | A | : |
G | D | G | DG | ||
G | C | G | DG | ||
: | D | D | D | C | : |