LONDON - MAY 24:  Queen Elizabeth II and US President Barack Obama toast each other during a State Banquet at Buckingham Palace on May 24, 2011 in London, England. (Photo by Rota/Anwar Hussein/Getty Images) *
WINDSOR, UNITED KINGDOM - JUNE 07:  The Queen With President Reagan At A State Banquet At Windsor Castle.  (Photo by Tim Graham Photo Library via Getty Images)
LONDON - NOVEMBER 19:  (NO UK SALES FOR 28 DAYS) HRH Queen Elizabeth II (2nd from L), U.S. President George W. Bush (L), First Lady Laura Bush and HRH the Duke of Edinburgh pose in the music room at Buckingham Palace on November 19, 2003 in London. The Queen was hosting a State Banquet at the Palace for the President and his wife, on the first official day of his 3-day visit to Britain. (Photo Royal Rota/Getty Images)
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)