I have a gg gfather named Thomas Dunne who lived in Clonmellon, Co Westmeath in mid 19th century. Of his sons (who moved to Kells, Co Meath c. 1872) I have not been able to trace sons James Joseph or Michael and their families. it is possible they , or at least one of them, travelled to Australia in the latter part of the 19th century. His youngest son Terence definitely went to Melbourne in the 1880s but returned to London and died there approximately 1890 (in his early 30s). I also know that two other brothers, John and Patrick, stayed in Ireland with Patrick (my ggfather) living in Kells, Co Meath.
If this rings any bells with anyone out there I would be glad to hear from you.