Ewan MacColl's real name was Jimmie Miller; Will Millar is another person entirely (former leader of the Canadian band The Irish Rovers, it appears). So far as I know, Ewan had no involvement with the song beyond publishing it in The Singing Island in 1960. His accompanying note is ambiguous, and avoids stating outright that Mary Brooksbank wrote the song. It has been suggested elsewhere that the song may be in part based on an earlier one, and that the tune may be adapted from tradition; but I've never seen anything more than vague suggestions. That is academic in any case; as it stands it is Mary Brooksbank's song, whether or not there were influences from elsewhere.

She was poor all her life, and lost money on her book Sidlaw Breezes, incidentally: it is to be hoped that no one begrudged her the modest royalty payments due on recordings of her songs.