Hi Gerard
Have you tried searching for a marriage (in Ireland I am assuming)?
http://pilot.familysearch.orgIs this Michael's birth entry:
MICHAEL RAHER Birth: 12 APR 1864 Tramore, Waterford, Ireland
Parents: MICHAEL RAHER and CATHERINE DUNPHY
Monica

Added: Can't be his entry can it

I see Michael is aged 78 in 1911. Wife is indexed as Hert, aged 64 - all the family showing as born in Co. Waterford.
You could always apply for a birth cert for one of the children, not sure how direct this line is to you.
Also, maybe the outside chance, as Didy suggested earlier that it could be Keat, for Kate, looking at the possible birth entry above for a Catherine Dunphy.