Robert Stewart, 1st Marquess of Londonderry

The Most Honourable The Marquess of Londonderry PC (Ire)
The Marquess of Londonderry by Hugh Douglas Hamilton.
Personal details
Spouse(s)	Lady Sarah Frances Seymour Lady Frances Pratt
Children	Robert Stewart, Viscount Castlereagh Charles William Vane, 3rd Marquess of Londonderry
Parents	Alexander Stewart Mary Cowan

Robert Stewart, 1st Marquess of Londonderry PC (Ire) (27 September 1739 – 6 April 1821), was an Irish politician and landowner, the father of politician Robert Stewart, Viscount Castlereagh. He was also an ancestor of Winston Churchill.

Stewart was born in 1739, son of Alexander Stewart, alderman of Londonderry in 1760, and Mary Cowan, daughter of John Cowan, alderman of Derry. He was also the nephew of Robert Cowan, the wealthy Governor of Bombay.

As the second son he expected to take up the linen trading business in Dublin. He did so, and it is for this reason that his first son was born in Dublin. His offices traded with many Baltic cities, including Saint Petersburg, Reval, and Memel. At the death of his older brother he moved to Ulster to be closer to his father and look after the family properties in Donegal, Londonderry, and Down.

He was elected to the Irish House of Commons in 1771 as member for Down. Between 1775 and 1783 he lived in Bangor with his wife while his father was living in Mount Stewart.

In 1779, worried by the presence of American and French vessels in the Irish sea, he organised the Newtownards Company of 115 men to act as fencibles. When he lost his seat in 1783 he was appointed to the Irish Privy Council. In the same year he inherited his father's properties in Co. Londonderry and Co. Down and settled at Mount Stewart, in the grounds of which he built the Temple of the Winds.