Came across this today- would think the best man to ask about details would be Pete Shepheard, who recorded Ian McLachlan playing it his way. You'll find it on a Springthyme cassette recorded at Kinross Festival about
1976. It may be on CD by now- ask Pete. Don't think Ian ever claimed it as his own composition, tunes run in the blood up there. I do recall that he played a big accordion most of the time that weekend, but Pete was keen to record him playing the melodeon. So at one stage, Ian borrowed my DG melodeon in a session & Vic Smith said my chin was nearly on the floor in amazement when I heard what he could do with it & Pete was determined to record him playing it. So Ian borrowed my old Hohner so if you want to hear what he did, some of it's on the recording, one of the best collections ever of such 'Island Music' (the title, I think).
I do recall asking Ian why he was leaving so early on the Sunday (just after the recording session) not realising the complications of a trip to Benbecula, where he lived and worked.