Just found your posting. In 1875, Fountain Villa, Waterside, Derry, was the home of William J. McCarter, JP, and his wife, Mary. They were the grandparents of my great-aunt, Norah (McCarter) Warbeke. You've correctly made a connection to J J Cooke, in that Cooke was the brother of Mrs. William McCarter, but I'm not aware that the Cookes owned the property; I believe that W J McCarter's will identified him as owner when he died from an accidental drowning. I can consult my files to see whether I can locate any references to household servants by name. W J McCarter was a capitalist, President of the Londonderry Gas Works, and a director of the northern branch of the RR. His son, William, owned and operated a peat farm for heating fuel.