I've found a 60 year old John O'Neill, police constable and widower, on the 1881 census:
James Mc Brearty Head Married Male 46 1835 Police Constable Ireland
Catherine Mc Brearty Wife Married Female 40 1841 Police Constable Wife Ireland
Catherine Mc Brearty Daughter Single Female 15 1866 Dressmaker Liverpool, Lancashire, England
Francis Mc Brearty Son Single Male 4 1877 - Liverpool, Lancashire, England
John O Neill Boarder Widower Male 60 1821 Police Constable Ireland
4, Gwendoline Street, Toxteth Park, Lancashire, England