He was born about 1463, in Maybole, Ayrshire, Scotland.
[1] He was a Privy Councillor of King James IV and was created Earl of Cassilis by him in 1502.
[3] Their son, Gilbert, 2nd Earl of Cassilis (29 Sep 1494 – 27 Aug 1527)[4] married Isabella Campbell daughter of Archibald Campbell, 2nd Earl of Argyll.
Their daughter Katherine married William Hamilton of Sorn and Sanquhar.
[5] After Agnes died David married Margaret Boyd, widow of Alexander Forbes and daughter of Sir Thomas Boyd, Earl of Arran and Mary Stewart, Countess of Arran, daughter of King James II of Scotland, but they had no children.