Upon his father's death, he took ownership of plantations in Grenada and Demerara, as well as the family home in Albany, London.
However, by 1830, he was living in Wellington Street, Westminster, with his wife, Elizabeth, née Vincent, and son William Duncan Stewart (born April 1829).
Also, a trustee of the Hope Vale estate in Grenada, in 1836 he claimed to have owned the "largest slave state" in Antigua between 1824 and 1826.
He became a director of the British West India Company in 1846, a member of the provisional committee of the Demerara Railway Company in the same year, a director of the London and Westminster Joint Stock Bank; and deputy chairman of the Universal Life Assurance Society.
[3][4] While his career was "undistinguished", "the bigoted anti-colour party in the West Indies could never get over his election by an English borough, but he was extremely popular with his constituents".