Princes' power! Following a tumultuous decade for the British monarchy that culminated in the tragic, untimely 1997 death of Princess Diana, heirs to the throne Prince William and Prince Harry have helped lift their family’s profile in immeasurable ways, according to royal biographer Andrew Morton.

"William and Harry have got the halo of Diana [around them], and are still surrounded by their mythic light, as it were," Morton explained in a March 10 interview on HuffPost Live. Left to their own devices, William and Harry have done their part to keep the monarchy on the up and up, but Morton says that it was when William married Kate Middleton that things really started looking up.

"Catherine has fit in nicely into their duo. She's added Madison Avenue glamour to the royal family," Morton says. "At the end of the day, the royal family is what they look like, and she's a good-looking kid."

Adding to Middleton's appeal, says the royal biographer and author of 17 Carnations: The Royals, the Nazis and the Biggest Cover-Up in History, is the Duchess' decision not to make waves at any point during her courtship and marriage to William. "For the people who want sensation, you're going to look elsewhere. Look to Harry and take him to Vegas," Morton joked to HuffPost Live, referring to the party prince's infamous 2012 romp — and strip billiards game with sexy coeds — in Sin City.

Speaking of Harry, who has spent recent months laying low in Verbier, Switzerland, and Stockholm, Sweden, Morton guesses that mum Diana would have "scratched her head" at her youngest son's wild antics. One of his worst faux pas? Deciding to wear a Nazi officer's uniform to a 2005 Halloween party — an action that resulted in him having to answer to his grandmother, Queen Elizabeth II.

"Very little gets to the Queen. She's the definition of impenetrable, but the thing that bothers her is anything that attacks the monarchy itself — the structure and fabric of the monarchy. When Prince Harry was going through the fancy dress department and thinking 'I think it's a good idea if I wear a Nazi uniform,' he should have thought what the Queen would think," Morton said. "That's the litmus test for all of them. When they don't do that, they usually get into trouble."

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