This is not so much a jig (hence the 16 bar sections) as a two step for dances such as the Britannia Two Step or Military Two Step, hence the alternative and more common name: The Shetland Two Step.
It was written by Shetlander Frank Jamieson.
In practice after the part in G you would go back to the part in A to finish.
By the way, this transcription is from the playing of Amy Geddes.
Ronald Cooper Jig
I really love playing this tune, its a great one for the box, and when I eventually learnt it I felt great satisfaction.
I was told that the tune was called Ronald Cooper, but the dance devised by Dixie Ingram to the tune was called the Shetland Two Step, and this is how we have the confusion of names.