Viscountess Castlereagh, c.1813 (w/c on ivory)

Amelia Anne Stewart, Marchioness of Londonderry (20 February 1772 – 12 February 1829), from 1794 until 1821 generally known as Emily Stewart, Lady Castlereagh, was the wife of the Georgian era Irish statesman Robert Stewart, Viscount Castlereagh, who from 1812 to 1822 was British Foreign Secretary and Leader of the House of Commons. Well-connected by birth to the aristocracy and wife of a prominent politician who was Britain's leading diplomat during the close of the Napoleonic Wars, Lady Castlereagh was an influential member of Regency London's high society.