Alexander Stewart (1699–1781)
Alexander Stewart (1697 – 22 April 1781) was an Irish landowner and ancestor of the family of the Marquess of Londonderry.
In 1743 Stewart successfully proved his right to the Cowan estate, and in 1744 he acquired estates in Comber and Newtownards in County Down. In ca. 1750 he built a house in Newtownards where he moved. The family home there was Mount Pleasant, later renamed Mount Stewart.
In 1759 the Member of Parliament for the city of Londonderry, William Scott, was raised to the bench. Initially William Hamilton was elected to succeed him, but the election was declared void. Alexander Stewart was returned in his place in April 1760, but he was also declared not duly elected. Eventually Hamilton represented the constituency from May 1760 until his death later that year. Stewart was not elected again to Parliament, but his sons and grandsons were, the Londonderrys becoming an important political dynasty.
Stewart was married on 30 June 1737 to Mary Cowan, daughter of John Cowan, alderman of Derry, and sister of the former Governor of Bombay Robert Cowan, who had recently died. Their children included two sons, Robert, born 27 September 1739, and Alexander, born 26 March 1746. Robert later became first Marquess of Londonderry. Stewart's family papers are in the Public Record Office of Northern Ireland.