Well, I obviously did not read the biog as carefully as I could have. While he does not say his mother went back to Auchterarder for the delivery, neither does he she did not. He just says, top of page 22, "I was born on 25 January 1915." Before that he talks about where his parents were living in the years prior to that. People moved back and forth, visited family, etc. Where in the biography is the bit I missed, Malcolm?

Domenico, this is what MacColl gives in The Singing Island :

There was a bonny shepherd lad kept sheep on yonder hill o,
He's laid aside his pipe and club and gane tae sleep his fill o
Fal the riddle, fal the riddle, fal the riddle di do

I assume you need the rest. I'll try to type it up when I can, if no-one else does so first.
Regards
Ewan