This is her article in thepeerage.com, "Elizabeth Seymour F, #10480, b. 1716, d. 5 December 1776
Elizabeth Seymour was born in 1716. She married Hugh Percy, 1st Duke of Northumberland, son of Langdale Smithson, on 16 July 1740. She died on 5 December 1776.
She was the daughter of Algernon Seymour, 7th Duke of Somerset and Frances Thynne. Her married name became Smithson. She gained the title of Baroness Percy.
Children of Elizabeth Seymour and Hugh Percy, 1st Duke of Northumberland
General Hugh Percy, 2nd Duke of Northumberland+ b. 14 Aug 1742, d. 10 Jul 1817
Algernon Percy, 1st Earl of Beverley+1 b. 21 Jan 1749/50, d. 21 Oct 1830."