I am not sure when my grandfather started to work there as a gardner as he was elsewhere on the 1911 census (Sorrento Road, Dalkey), my father was born at Court - na farragh in 1917 and I know my grandfather died in Liverpool in 1925 but I am not sure when they moved from Ireland.
My grandfather would also at that time left his original children in Ireland but as they were late teens / early twenties this is possible, but the youngest from his first marriage would have been quite young.