Steuart’s father, who maintained in his will that he was one of the Grantully branch of that family (they relinquished trusteeship of his estate at probate) had business interests in Calcutta, administered for him in later life by his brother-in-law William Hastie (d. 1818) and the latter’s sons. He purchased a 315-acre estate and several holdings in Alderston and nearby Haddington and in 1805 married a granddaughter (d. 1823) of the 3rd earl of Dunmore, on whom property in Nicolson Street, Edinburgh, had been settled. Her brother William Drummond (d. 1828), a writer and diplomat, represented St. Mawes, 1795-6, and Lostwithiel, 1796-1802, on the treasury interest. Robert Steuart died 1 Feb. 1827, worth an estimated £18,000 at probate (including two original shares in East India Company stock), having willed his estates and the bulk of his fortune to Steuart, the eldest of his four children, then an Oxford undergraduate. With the consent of his trustees, his brother-in-law Norman Pringle and the minister of the episcopal chapel in Haddington, James Craill, in July 1827 at North Berwick he married Maria Dalrymple, the daughter of an East Indian army colonel who had died in Madras in 1821.
Steuart became a commissioner of supply for Haddingtonshire, where he rallied support for the reformers and the Grey ministry at mass meetings and dinners in the winter of 1830-1. After successfully canvassing the councils of Jedburgh and Haddington (who appointed him their delegate), he declared for Haddington Burghs at the general election precipitated by the reform bill’s defeat and was returned by three votes to two after a riotous contest dominated by the kidnapping of the Lauder baillie.
Advocating the ballot, civil registration and church reform, Steuart regularly addressed reform meetings in 1831-2, canvassed continuously and was returned unopposed for Haddington Burghs as a Liberal at the general election of 1832.
