I can trace back to John Kavanagh, born in Ashtown, Co Dublin; died 29 Sept 1887. His wife was Ellen Corcoran. They had several children, Anna Beatrice (my grandmother, b 1880 in Mulhudart), Matthew, Michael John, Teresa. Michael John Kavanagh was in the Leinster Regiment and served in the Boer & WW1; one of his children was a sculptor.
I don't know when John was born, but his sister Anne was born about 1839: I have her baptism certicate
Baptism Certificate. "Church of St Maccuilin, Lusk, Co Dublin. This is to certify that Anne Kavanagh, daughter of John Kavanagh & Mary Judge was baptised on the 17th day of January 1840. The sponsors were Patrick Devine and Anne Murphy"
I know that there were other relations in Dublin, including cousins called Ashton and Harford. Both John and Ellen died young and my grandmother went to live with her Aunt in London.