Thomas married Elizabeth Starkey, a young woman of humble origin, They lived happily together, and had three daughters: Susan, married in 1796 to the 3rd Earl of Guilford; Frances, married in 1800 to John, 1st Marquess of Bute; and Sophia, married in 1793 to Sir Francis Burdett.
Mrs Coutts died in 1815. Soon after her husband married the popular actress, Harriot Mellon,…