Prince Philip and Prince William.Photo: Chris Jackson/WPA Pool/Getty

Prince Philip, who died on April 9 at the age of 99, played a major role in preparing his grandsonPrince Williamto be the monarch one day.
“Philip was crucial in helping coach William as a future King,” historian Robert Lacey, author of the bestselling biographyBattle of Brothers, tells PEOPLE in this week’s cover story. “It was Philip’s idea to set up the lunches between William and his grandmother. When the time came for the Queen to talk business with William, Philip would quietly excuse himself because he didn’t feel that the constitutional side of the Queen’s job was something he wanted to interfere in.”
Prince Philip, who insiders say was the glue behind the royal family for more than 70 years, passed on “elements of the serious and the fun” to grandsonsPrince William, 38, andPrince Harry, 36, adds royal biographer Penny Junor.
Prince Harry and Prince Philip.Phil Walter/Getty

Harry “very much got his sense of duty and active service from his grandfather,” says Junor. “Because Harry is a much more relaxed character, he was able to bring in the more frivolous memories of his grandfather” in histribute statement, including references to barbecue and beer.
Prince William, Queen Elizabeth, Prince Harry and Prince Philip.Getty

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Harry and William were seen chatting alongside William’s wifeKate Middletonas they left St. George’s Chapel in Windsor Castle. The siblings continued speaking as they walked away from the church, as Kate stepped back to talk with Sophie, Countess of Wessex.
Prince Harry and Prince WIlliam.

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“It has been a very difficult time,” a well-connected royal insider says of the past year. “The Duke was the head of the family, and if there were any time they were going to come together, it’s now.”
source: people.com