Chatham House, the Royal Institute of International Affairs, is a non-profit, non-governmental organisation based in London whose mission is to analyse and promote the understanding of major international issues and current affairs. It is the originator of the Chatham House Rule. It takes its name from its premises, a Grade I listed 18th-century house in St. James's Square designed in part by Henry Flitcroft and occupied by three British prime ministers, including William Pitt, 1st Earl of Chatham.In the University of Pennsylvania’s 2014 Global Go To Think Tanks Report, Chatham House is ranked the second most influential think tank in the world after the Brookings Institution, and the world's most influential non-U.S. think tank. In 2009, Chatham House was also named the top non-U.S. think tank by Foreign Policy magazine, which listed it as one of the top ""scholars"" for being among a handful of stars of the think-tank world who are regularly relied upon to set agendas and craft new initiatives.The current chairman of the Council of Chatham House is Stuart Popham and its director is Robin Niblett. The research directors are Rob Bailey, Patricia Lewis, Paola Subacchi and Alex Vines.Chatham House has distinguished presidents from each of the three main political parties at Westminster: Sir John Major, former UK Prime Minister, Lord Ashdown, former EU Special Representative in Bosnia and Herzegovina and former leader of the Liberal Democrats, and Baroness Scotland, the former Attorney General.