The Flagon Reel
The Flagon Reel is from the Vickers’ manuscript from North East England in the 1770s. It clearly shares lineage with the "Flogging Reel" played in the Irish tradition, but shows a distinctly Northumbrian feel for the tune.
The whole manuscript can be viewed online from the Folk Archive Resource North East (FARNE).
RE: The Flaggon
In Cape Breton they play the Flaggon in Gmix. I believe what actually happened was that the Flaggon was originally a Northumbrian/Scottish tune, and then because of the limitations of the Uilleann pipes, the tune was put into Gmaj, and that’s how a lot of Irish musicians still play it. It loses a lot in Gmaj though in my opinion.