Matthew,
I haven't heard John sing it and didn't know it was in his repertoire. I guess I need to read the sleeve notes a bit more...
I have the two early Clutha albums which John sings on and I know it's not on any of them. Nor is it on their recent (Greentrax?) one. I don't know of another Greentrax recording by Stramash apart from their "McGinn of the Calton" presentation, not that that should imply a definitive knowlegde of the Greentrax label (or Clutha/John Eaglesham recordings for that matter) but I'll check with a man who should know.
You've got me intrigued now... The more I think of him as the source of the tune the more I can actually just about hear him doing it in a late night session...
Andy