Wills established the Ditchley Foundation for the promotion of international relations and subsequently donated the house to the governing trust.[4] King James VI and I and Anne of Denmark visited on 15 September 1603 with the French ambassador and a duke, whom Arbella Stuart called the "Dutchkin.She worked on it with Sibyl Colefax (Mrs Bethell of Elden Ltd having died in 1932) and the French decorator Stéphane Boudin of the Paris firm Jansen.On the outbreak of war, the security forces were concerned by the visibility of both Churchill's country house, Chartwell – its high site, and its position south of London, making it an easy returning-home target for German aircraft – and the Prime Minister's official retreat of Chequers, which had an entrance road which was clearly visible from the sky when illuminated by moonlight.The last weekend Churchill attended Ditchley as his official residence was Tree's birthday on 26 September 1942, and his final visit was for lunch in 1943.Shortly after the end of the war, Tree divorced Nancy and married Marietta Peabody Fitzgerald, an American woman he had met while working for the Ministry of Information.In 1958 Wills set up a trust, the Ditchley Foundation, which aims to promote international (especially Anglo-American) relations, and which still owns the house today.[25] It was a colonnaded house with outbuildings, threshing floors, and a granary with capacity for the produce of about 1,000 acres (400 ha) of arable land.[31] Grim's Ditch, which passes through the present park and estate, is an ancient boundary believed to have been constructed during the Roman occupation of Britain in about the 1st century AD.