His house was number 76 Welbeck Street, Westminster. Once when in Yorkshire, it is said that he made a point of not visiting his property, which was of considerable extent, "lest he should be involved in the troubles of a landed proprietor". He was an intimate friend of John Horne Tooke, to whose house at Wimbledon Bosville used to drive down in a coach and four to dinner every Sunday during the spring and autumn for many years, and is mentioned in his "Diversions of Purley". Possessed of a large fortune he was exceedingly generous with his money, and was unbounded in his hospitality. Every weekday he used to receive some of his friends at dinner at his house in Welbeck Street. The party never exceeded twelve in number, and the dinner hour was always five o’clock punctually. A slate was kept in the hall, in which any of his intimate friends might write his name as a guest for the day, Besides Horne Tooke, Sir Francis Burdett, 5th Baronet, Lords Hutchinson and Oxford, Parson Este, and others, often availed themselves of this privilege. The first stroke of five was the signal for going downstairs, and the host made a point of never waiting for any of his guests. In accordance with his favourite maxim, namely "Some say better late than never; I say better never than late", an old friend who arrived one day four minutes late was refused admittance by the servant, who said that his master was "busy dining". Though his health declined and his convivial powers failed, he still continued his dinner parties to the last. Even when compelled to remain in his bedroom, the slate was hung in the hall as usual, and on the very morning of his death he gave his orders for the dinner at the usual hour. He died unmarried at his house in Welbeck Street on 10 December 1813 in his sixty-ninth year, and was buried on the 21st of the same month in the chancel of St Giles in the Fields. By his will left nearly the whole of his fortune and estates to his younger nephew Col. Hon. Godfrey Macdonald (later Godfrey Macdonald, 3rd Baron Macdonald of Slate) (1775–1832), who in 1814 in accordance with the will, by royal licence changed his surname to Bosville (and later in 1824 to Bosville-Macdonald). He was the second son of William's sister Elizabeth Diana Bosville (d.1789) and her husband Sir Alexander Macdonald (d.1795) (later 1st Baron Macdonald) and therefore had no expectation of a paternal inheritance.