 She married William Pole-Wellesley, 4th Earl of Mornington, who assumed the additional surnames of Tylney and Long.The 4th Earl of Mornington's wife was known in fashionable London society as "The Wiltshire Heiress", as she was believed to be the richest commoner in England.Her estates in Essex, Hampshire and Wiltshire were said to be worth £40,000 per year in rents (£3,500,000 in 2016).