 Grace's half-sister Elizabeth Smythe was the wife of Sir Thomas Monk (1570–1627) of Potheridge, Devon, MP for Camelford in 1626, and mother of the great general George Monck, 1st Duke of Albemarle, KG (1608–1670).It was largely due to his close kinship to his first cousin the Duke that Sir Bevil's son Sir John Granville was raised to the peerage in 1660 as Earl of Bath, and was also granted the reversion of the Dukedom of Albemarle in the event of the failure of George Monck's male issue.His third son was Bernard Granville, father of George Granville, 1st Baron Lansdown (1666–1735).