achievements in such diverse fields as printing, building a mechanical calculator, steam navigation, optics, musical notation and fire-proofing in buildings were overshadowed at the time and subsequently by his reputation, as the self-styled "Citizen Stanhope", for eccentricity and political radicalism. Philip Henry Stanhope, 4th Earl Stanhope, was a gifted amateur landscape gardener and architect, half-brother to Lady Hester Stanhope, and the legal guardian of Kaspar Hauser. Philip Stanhope, 5th Earl Stanhope, was the driving force behind the foundation of the National Portrait Gallery and the Historical Documents Commission: writing as Viscount Mahon he was a distinguished 19th-century historian and established the Stanhope Essay Prize at Oxford. Arthur Stanhope, 6th Earl Stanhope, was a Conservative MP before inheriting and served as First Ecclesiastical Estates Commissioner from 1878 to 1903. Both his brothers made their careers in politics. The Rt Hon Edward Stanhope (Conservative) was a reforming Secretary of State for War (1887–1892), while the 1st Lord Weardale (Liberal) was president of the Inter-Parliamentary Union (1912–22) and of the Save the Children Fund. James Stanhope, 7th Earl Stanhope (also 13th Earl of Chesterfield), was a Conservative politician who held office almost continuously from 1924 to 1940, serving in Cabinet posts from 1936 under Baldwin and Chamberlain. He founded the National Maritime Museum at Greenwich. Having no children of his own and his only brother having been killed in the Great War, the last Earl Stanhope wished to create at Chevening a lasting monument to a family that had provided for two and a half centuries politicians across the political spectrum and no fewer than five fellows of the Royal Society. He therefore drafted what became the Chevening Estate Act 1959 to ensure that the estate would not be broken up after his death, but would instead retain a significant role as a private house in public life. The ownership of the property would pass to a Board of Trustees, who would maintain it as a furnished country residence for a suitably qualified nominated person chosen by the prime minister. The nominated person would have the right to occupy the house in a private capacity and would pay for their private living expenses. The Board of Trustees would maintain the house and estate by means of their stewardship of the estate, with no grant from the Government. The Act was passed with cross-party support and, as amended by the Chevening Estate Act 1987,