 Lord Mahon succeeded to the title of Earl Stanhope on the death of his father on 24 December 1875.He was appointed First Church Estates Commissioner in December 1878, and served as Lord Lieutenant of Kent from 1890 to 1905.He married Evelyn Pennefather, daughter of Richard Pennefather of Knockeevan, County Tipperary by his wife Lady Emily Butler, daughter of Richard Butler, 1st Earl of Glengall.