The Obama's Host the Queen and the Duke of Edinburgh for Dinner

LONDON, ENGLAND - MAY 25: Queen Elizabeth II signs the guest book as she bids farewell to U.S. President Barack Obama (L) and First Lady Michelle Obama, watched by the Duke of Edinburgh (2nd R) at Winfield House - the residence of the Ambassador of the United States of America, in Regent's Park, on May 25, 2011 in London, England. The 44th President of the United States, Barack Obama, and First