He died at Barlavington. He was survived by his daughter from his first marriage, and two sons and three daughters from his second marriage. Due to differences between English law and Scottish law, one son, Sebastian (born prior to his parents' marriage), inherited the Scottish title, becoming 9th Baronet of Balcaskie and 11th Baronet of Anstruther (both being Nova Scotia or Scottish Baronetages). Obituaries to Sir Ian noted, erroneously, that the Great Britain Baronetcy of Anstruther (1798) had passed to his other son Toby (born after Sir Ian's second marriage). He left an estate valued in excess of £35,000,000.