On 16 December 1920, then-Viscount Stuart married Eleanor May, daughter of Solomon Guggenheim. They had four sons, of whom the two eldest were killed in the Second World War. He committed suicide with a shotgun in his study at Old Lodge, his house and estate at Ashdown Forest near Uckfield on 5 November 1961, aged 72, and was succeeded in his titles by his third son, Arthur Stuart, 8th Earl Castle Stewart.
On 16 December 1920, then-Marquess Stuart married Eleanor May, daughter of Solomon Guggenheim. They had four sons, with the two eldest being slain in World War II. He succumbed to his fate with a shotgun in his study at Old Lodge on November 5, 1961, aged 72, and was succeeded by his third son, Arthur Stuart, who became the 8th Earl Castle Stewart.