Who married James Stuart-Mackenzie?

James Stuart-Mackenzie (30 October 1718 – 8 April 1800) was a Scottish politician and joint founder of the Royal Society of Edinburgh in 1783. The second son of James Stuart, 2nd Earl of Bute, he served as Member of Parliament for various Scottish constituencies of the Parliament of Great Britain from 1742 to 1780. Stuart-Mackenzie was the British Minister at Turin from 1758 to 1761. He was made a Privy Councillor in 1761, and served as Keeper of the Privy Seal of Scotland from 1763 to 1765, and again from the following year until his death in 1800.