Can't get that link for Cilla's songbook to work.
Seriously, I'm not all that surprised to learn of 'conflicting' accounts. Belle was a very accomplished writer as well as a singer, and my instinct would be that this, by and large, is her own song. It may have mainly come from the 'old ploughman' in Blairgowrie, but I think that Diz's instinct may also be accurate about the 'Irish lilt' that would allow for another source.
My guess - and this is only a guess - is that Belle brought together several elements from her experience and made them into a complete song. There are some Irish 'bits', plus something from music hall or cornkister style, which she welded together to make the song as we have it today. Perhaps Sheila Stewart might be able to say a bit more, but maybe Belle didn't tell her!