The first of the Denys family to have resided at Dyrham rather than at the Denys ancestral manor of Siston, appears to have been Sir William Denys(1470–1533), son of Sir Walter Denys(d.1505), who is depicted on the Denys monumental brass in the Church of Olveston, which manor was also held by the family, and Agnes Danvers.
Sir Gilbert Denys(d.1422) of Siston, Gloucestershire was probably born in about 1350 in Glamorgan, probably the son of John Denys of Waterton.