Marriage in January 1918 between William Joseph O'Reilly, aged 20, an engineer
address Grosvenor Gardens, Harolds Cross, father Michael O'Reilly, a gardener
and
Eveleen O'Mahony, aged 19, address 132 Harolds Cross, father Daniel O'Mahony an agricultural expert.
I can find the O'Mahonys in the censuses and on irish genealogy but I can't get any further back with the O'Reillys.
There is also a birth certificate in 1918 and a marriage certificate in 1934 giving Grosvenor Gardens as the address.