I heard this one on Natalie MacMaster’s "Live" CD 1, but there was an error when that recording was submitted to this site and it isn’t being listed… Good tune.
This sounds like a relative of the hornpipe, The Flowing Tide
This tune is printed at least twice in Ryan’s Mammoth Collection, as "The Picnic" and, in A, as "Seventh Regiment," the latter attributed to one Conn Higgins. O’Neill borrowed it for his collection as "Higgins’ Best," as he already had another Higgins’ Hornpipe. Now better known in a different setting in G as "The Flowing Tide."
There is a lovely version of this tune recorded on Jamie Laval’s first album "Shades of Green", following "Farewell to Loch Katrine".
I had a devil of a time finding out what this fantastic tune was called!
Higher Octave and Shift to D
As printed in Ryan’s Mammoth Collection/Cole’s 1000 Fiddle Tunes, the first part is an octave higher. That calls for a shift to higher position on the fiddle, so some NY fiddlers (including Paddy Reynolds and Andy McGann) shifted the tune to D.
Correction, and Composer credit
Scratch that last comment - McGann and Reynolds played it in A as it appears here. My memory was faulty. The original version of "The Picnic" was composed by a George Saunders, who published it in his "New and Scientific Self-Instructing School for the Violin… Intended for Beginners, Amateurs, Business Players, and Teachers. In Three Parts, Complete in One," published in Boston, Providence and Buffalo in 1847. Elias Howe borrowed it from that book, and also inlcuded the more difficult "7th Regiment" version in "Ryan’s Mammoth Collection." O’Neill borrowed the "7th Regiment" for his 1903 "Music of Ireland."