WASHINGTON, DC - MARCH 19: Charles, Prince of Wales sits as he attends a meeting with United States President Barack Obama (not pictured) in the Oval Office of the White House on March 19, 2015 in Washington, D.C. The Prince and Duchess are in Washington as part of a Four day visit to the United States. (Photo by Ron Sachs-Pool/Getty Images)

WASHINGTON, DC - MARCH 19:  Charles, Prince of Wales sits as he attends a meeting with United States President Barack Obama (not pictured) in the Oval Office of the White House on March 19, 2015 in Washington, D.C.  The Prince and Duchess are in Washington as part of a Four day visit to the United States.  (Photo by Ron Sachs-Pool/Getty Images)