 He assumed the additional surname of Gathorne by Royal licence in 1878 and when his father was elevated to the peerage as Earl of Cranbrook in 1892, he gained the courtesy title of Lord Medway.Cranbrook was elected to the House of Commons for Rye in 1868, a seat he held until 1880, and later represented Mid Kent from 1884 to 1885 and Medway from 1885 to 1892.In 1906 he succeeded his father as second Earl of Cranbrook and took his seat in the House of Lords.