Twas In The Month Of January
1) This is not really a jig but a slow air.
2) It’s not really in F major but C mix. (Both have the same scale and key signature with a Bb.)
Above comments relate to the options available when adding a new tune.
3) I think of this more as a "song" rather than just a "tune". It appears elsewhere on this site as an alternate title under "Erin’s Shore". While there are melodic similarities, they are neither the same in melody nor word.
4) The setting posted here is my best attempt to transcribe the song as sung a capella by our singer a few days ago. You can hear her version here: http://www.roadstohome.net/guest/Month-of-January.mp3