Hello Nick,
I noticed this while fishing around on the net. I know that you posted this quite some time ago so maybe you can help. Maria Callaby is my g-g-grandmother. My research tells me she married a Peter McBow from Belfast at Jerry's Plains in 1867. I believe her mother Anne's name was Ann Irwin when she left Londonderry, N Ireland on the ship Adam Lodge with free passage and her name subsequently became Irving. To enable me to go back into Irish records, can you confirm if that is your findings?
Many thanks