Amelia Stewart, Viscountess Castlereagh

Amelia Anne Stewart, Marchioness of Londonderry, nicknamed "Emily" and, from 1794 until 1821 generally known as Lady Castlereagh, was the wife of the Georgian-era Anglo-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.