He was the younger brother of Thomas Willys, both being sons of Richard Willys, a lawyer and Lord of the Manors of Fen Ditton and Horningsey, Cambridgeshire, by Jane, daughter and heir of William Henmarsh, of Balls, in Ware, Hertfordshire.
The baronetcy passed to Sir Thomas Fox Willys, of Warlies (30 June 1661 - 1701) who was said by his grandfather Thomas Fox to have been born "bereft of his wits" and died unmarried and without children at the age of 59.