New married couple, the Duke and Duchess of Cambridge share a loving look as they leave the ceremony. Maybe Kate is smiling because she's got the best hat in house, a Cartier "halo" tiara.
According to Beatrice Aidin, a British journalist and style watcher, Prince William's headgear has hidden significance, "As with everything British, a hat signifies social standing. But it does come from the military and it is significant that military and millinery are two closely connected words."