There is one golden rule that Kate Middleton never breaks – and it was taught to her by none other than Prince Philip.
Stepping down at the age of 96, Prince Philip was the longest-serving consort in British history and served as patron, president or a member of more than 780 organisations.
Because of his unwavering duty to his role, Philip was in a position to offer advice to new members of the royal family, including the late Princess Diana and Kate Middleton.
Prince Philip's 'golden rule'
According to royal author Gyles Brandreth in his biography, Philip The Final Portrait, the Prince doled out wisdom from his decades-long stint as a working royal and even shared a golden rule of royalty with Kate.
The author writes that Philip advised the future Princess of Wales to never look at the camera. He reiterated that the late Queen never looked at the camera, but rather at the person they were talking to.
He wrote that Philip said: "If you believe the attention is for you for your personally, you're going to end up in trouble.
"The attention is for your role, what you do, what you're supporting. It isn't for you as an individual. You are not a celebrity. You are representing the Royal Family. That's all."
According to the author, Philip, who was seen as the mentor of the royals, worried about fame going to newer members of the royal family's heads.
Despite his concerns, the late Duke of Edinburgh was reportedly "relieved" that his grandson Prince William had found a "level-headed girl' in Kate.
Gyles himself added, “I have been on walkabout with the Duchess of Cambridge. She does not look at the camera. Whenever she is interviewed, Catherine talks about the matter in hand, never about herself.”
Prince Philip's soft side
Beginning life in the British royal family as an outsider, Philip quickly became one of the most beloved and stoic forces within the family.
However, Philip was also remembered for being a mentor on how to navigate the throes of royal life to newer members of the family such as Princess Diana and Meghan Markle.
"When (Diana) found the restrictions of royal life difficult, it was Philip who helped her," writes royal author Ingrid Seward in her book Prince Philip Revealed.
"Once she was married, she never sat next to her husband; she was always sat next to Philip at the endless black-tie dinners, and he took care of her.
"Diana found the Balmoral dinners a massive strain and the atmosphere stifling," Seward continues.
"When the piper came around the table after dinner with his kilt swirling and his pipes whining, she couldn't wait to leave the room."
Meghan Markle also revealed that it was Prince Philip who gave her a warm welcome during her early days with the royal family.
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"At dinner, I was sat next to H's grandfather and I just thought it was so wonderful and I was like, 'Oh we chatted and it was so great and I talked about this and talked about this'," she later recalled.
However, Prince Harry later informed her that she "had his bad ear," to which, Meghan laughed: "I was like, 'Oh - well, I thought it went really well.'"