From her Wikipedia article. She was unhappily married to Arthur Wellesley, Duke of Wellington and victor at Waterloo. She lost a brother in the Battle of New Orleans, an auxiliary battle in the Napoléonic wars fought after the warring countries had signed a truce but before word could be sent to the combatants.
Lady Catherine may be wearing a vee-neck lace cape tied with a bow over a chemise and bodice with a sweetheart neckline as well as a wrap.
Keywords: 1810, Swinton, Catherine Pakenham, Kitty Pakenham, Catherine Wellesley, Duchess of Wellington, Pakenham family, Wellesley family, Duchess, British, straight coiffure, ribbon headdress, cape, lace, bows, long full sleeves, cuffs, bracelets, wrap