I've now had a chance to play the 'Muckle Sangs' CD and listen again to the two fragments that Bert Lloyd might have based his tune on. I remember that, when I first played it, it was the Betsy Johnson version that most reminded me of Bert's tune - but now that I've played it again I suspect that he might have taken elements from both Betsy's version and that of Willie Whyte. Or then again, I could be talking complete rubbish! Please, will someone with more knowledge of how tunes work listen to these two tracks and tell me what they think of my theory - even if it's to tell me that I'm wrong.
I've long suspected that both Bert and Ewan MacColl were both capable of taking tunes from oral tradition and sort of 'reverse-engineering' them. The trouble is we know so little about their methods - especially Bert's.