This tune is based on an old Gaelic Air “Caidil mo Ghaoil”, which translates to “Sleep my Love”. It is used as a taps signal call in Highland Regiments, and the Queen requested that her piper Pipe Major Paul Burns play it at Westminister Abbey. It is played quite slowly and the pipes add ormaments to the longer notes, so you can try doing that on the fiddle once you get used to the tune, which is in the Key of D.
Here is a piper playing a version similar to our sheet music for fiddle. Sleep Dearie Sleep Lone Piper