Here's a better midi, this one having been produced with bagpipe notation software for the tune collection on the Canadian Scottish Regiment Pipes and Drums site.
As for many slow airs on the pipes, the interpretation of the notation is largely up to the piper. 'Written as' and 'played as' are two different things. There are even variants of time signature in the pipe notation.
The song version is quite different again. For that I suggest tracking down the version sung by Isla St. Clair on her CD titled 'When the Pipers Play'. It's excellent!
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