Hi Jack,
I'll need to listen to Iain's singing again, but I am of the Beatles generation and don't remember ever noticing that connection before! I'll tell him to check out this forum himself - tho' lots of other people have picked up the song very few of them have ever heard the original, so they have adapted it, both words and music!!! For example the link from John McKenzie (immediately after your comment) shows a group singing a version that to my ear is a distant cousin of the one Iain wrote!
- I can tell you exactly how the song moved out into the wide world - I sang an unaccompanied version in Jean Redpath's singing class at Stirling University probably in 1985 or 86; Chris Miles was visiting the class that day and picked the song up, sang it at lots of festivals that year - and from then on it spread! However - the way I sang it was not how Iain wrote / sings it (for a start I can't play guitar) so immediately there were changes in the style, tho' I am pretty sure my words and tune would have been accurate. I guess songs are like children, once they are out in the big world you can't control them any more!!!
I know Iain thinks a lot about his tunes, making sure they are original - have you heard him singing his song? Not sure if I have the expertise to send it to you but maybe we can get to a session in Edinburgh some of these days?!