On his death Duncan left a family of four daughters, and, besides the eldest son who succeeded to the peerage, a second son, Henry, who died a captain in the navy and K.C.H. in 1835.
On his death Duncan left a family of four daughters and two sons. His eldest son succeeded to the peerage and later became Earl of Camperdown; the second son, Henry, died a captain in the navy and K.C.H. in 1835.