Britain's Prince William (L) and his wife Catherine, Duchess of Cambridge and Prince Harry (R) leave the VIP marquee during a military awards ceremony, A Night of Heroes, at the Imperial War Museum in central London December 19, 2011.[Photo/Agencies]

Britain's Prime Minister David Cameron, and his wife Samantha, arrive at a military awards ceremony, A Night of Heroes, at the Imperial War Museum in central London December 19, 2011.[Photo/Agencies]