The “Swedish Jig"’", sometimes known as Arthur Darley’s, is a most unusual tune.
In the first part of the tune a time signature change occurs in bar 7 from the standard 6/8 to a 9/8, just for one bar, before reverting back to 6/8. In effect you play an extra half a bar.
Also the first part consists of 12 bars rather than the standard eight.
The A part is in D Major, but changes to D Minor for the second part, and then back to D Major for the third part. Both the second and third parts have 8 bars.
The chords are D, A, G, Dm, A7 and Gm.