Have you discounted this one in 1861 - Trefor Newygdd, Llansadwrn, Bangor, Anglesey,
I realise that John gives his fathers occupation as Labourer
Certainly possible. I haven't discounted this one, I've kept note of it, but I'm not sure how likely it is. I
The occupation is off, as you mention, and the children's names don't really match the names John and Mary gave to his children, not that they all should, but its something to look for. I would have to follow up on this lead again though, I made notes on some potential records for John years ago, but I've lost them somewhere.
I was questioning if the nurse on the 1881 census might actually be his mother, under her maiden name, I have seen that before, especially if parents weren't married, or were just pretending to be. But again, probably not very likely, just a fringe possibility in absence of any concrete records.