Britain's Catherine, Duchess of Cambridge (L) speaks with US First Lady Michelle Obama at Buckingham Palace, in central London, on May 24, 2011. US President Barack Obama Tuesday basked in the lavish royal pageantry of a state visit to Britain, given an extra dash of glamour by a brief encounter with Prince William and his bride Catherine. But the 24-hour demands that follow a US president everywhere shadowed the London pomp, as Obama took time out to say he was 'heartbroken' at the toll of vicious tornados which ripped across the US midwest, killing 116 people.  AFP PHOTO / TOBY MELVILLE/POOL (Photo credit should read TOBY MELVILLE/AFP/Getty Images)