He was the eldest son of William McDowall, Member of Parliament for
Renfrewshire from 1768 to 1774, and Elizabeth Graham. He was a partner in the firm of Alexander Houston & Co., a major Glasgow firm trading in the West Indies, which failed in 1801. He was
Lord Lieutenant of Renfrewshire from 1794 until his death, and
Rector of Glasgow University from 1795 to 1797. ==Family==