However, Harrold said he's noticed one area in which Prince William differs quite a bit from his grandmother. "The late Queen always used to say that she put monarchy over family," he said. "Admittedly she did occasionally put family first in ways that contradict this, but she did say it often. I think William is very different."

Kate married Prince William, 40, on this day at Westminster Abbey in 2011. According to the documentary, 'William & Kate: The Journey', Kate was encouraged by royal officials to wear her hair up, something she stood firmly against.