Britain's Queen Elizabeth (R) and the Duke of Edinburgh (L) pose with Mexico's President Felipe Calderon and first lady Margarita Zavala in Buckingham Palace in London before the state banquet during the state visit of the President to London March 30, 2009. Calderon is set to attend the G20 summit in London on tackling the global financial crisis on April 2 while he is in the city, as Mexico is one of the world's leading emerging economies.       AFP   PHOTO/Stephen Hird   ROTA POOL (Photo credit should read STEPHEN HIRD/AFP/Getty Images)