She is also known for her affair with Lord Byron in 1812.
Her husband was The Hon.
William Lamb, who later became Viscount Melbourne and Prime Minister.
However, she was never the Viscountess Melbourne because she died before Melbourne succeeded to the peerage.
She was the only daughter of Frederick Ponsonby, 3rd Earl of Bessborough, an Anglo-Irish peer, and Henrietta, Countess of Bessborough, and related to other leading society ladies, being the niece of Georgiana Cavendish, Duchess of Devonshire, and cousin (by marriage) of Annabella, Lady Byron.