Amelia Byron

http://thepeerage.com/p1176.htm#i11751

http://www.geneall.net/U/per_page.php?id=140908

Amelia Osborne (nee Darcy), Marchioness of Carmarthen and de jure 12th Baroness Darcy de Knayth and 9th Baroness Conyers and 5th Countess of Mértola (12 October 1754 – 27 January 1784) was a British peeress and a Portuguese countess.

Amelia was the only child of the 4th Earl of Holderness and his wife, Mary. On 29 November 1773, she married Francis Osborne, Marquess of Carmarthen and they had three children:

Lord George William Frederick

Lord Francis Godolphin (later Baron Godolphin)

Lady Mary Henrietta Juliana (who married the 2nd Earl of Chichester).

Lord and Lady Carmarthen divorced in May 1779 and a month later, Amelia then married John "Mad Jack" Byron (the father of the poet, Lord Byron) and they had one daughter, Augusta. A year earlier, Amelia had inherited the right to her father's baronies of Darcy de Knayth and Conyers (although this wasn't confirmed until 1798, long after her death) and also inherited the Portuguese countship of Mértola from him. On her own death in 1784, they were inherited by her eldest son, George.

On the death of the 4th Earl of Holderness the Earldom of Holderness became extinct but the Baronies of Darcy de Knayth and Conyers and the right to the Countship of Mertola passed to his only daughter and sole heiress, Lady Amelia Osborne, Marchioness of Carmarthen

Lady Amelia Darcy, Bss Darcy & Conyers, b.12 Oct 1754, d.27 Jan 1784; m.1st London 29 Nov 1773 (div 1779) Francis Godolphin-Osborne, Marquess of Carmarthen [later, 5th Duke of Leeds] (29 Jan 1751-31 Jan 1799); m.2d London 1779 John Byron (7 Feb 1756-10 Apr 1786)