LONDON, ENGLAND - OCTOBER 21: Catherine, Duchess of Cambridge and Prince William, Duke of Edinburgh smile at each other during a ceremonial welcome for the President of Singapore at Horse Guards Parade on October 21, 2014 in London, England. The President is at the beginning of his four day stay during which he will hold a bilateral meeting with Prime Minister David Cameron. (Photo by Toby Melville - WPA Pool/Getty Images)