Steve. We talked about this briefly at Sheffield TSF. I agree that Cecila Costello's is a patchwork, but I am not sure it is unique. I have vague memories of hearing that the poet John Clare collected a similar version, which presumably will be in John Clare and The Folk Tradition.

Also Hugh Shields contributed an article called The Grey Cock: Dawn Song or Revenant Ballad? to Emily Lyle's collection, Ballad Studies. Again, my memory is vague but I think he argued that the supernatural element in Willie'O (Mrs Costello's Grey Cock also?) was introduced to satisfy C 19 morality. IE., it was a way to explain the presence of a mortal male in an unmarried woman's bedroom.

Curiously enough, at the 1978 Beleek singing weekend, a local traditional singer (one of Tom Munnelly's discoveries, I think)introduced a pretty standard non-supernatural version of The Night Visiting Song by saying that it was about a ghost. I asked Munnelly whether someone might have suggested that to the bloke and he said no. He'd met the guy just that afternoon in the pub and that was what he'd said when he'd sang it then.

Apologies if this repeats anything you already know, and apologies once again for the vagueness. But I am totally knackered and brain deadened and not yet recovered from the trip home after Gerry O'Hanlon's funeral.