Before Prince Philip passed away, he bestowed some precious advice on Kate Middleton, the Princess of Wales. Prince Philip passed away four years ago at the age of 99. He was the longest-serving royal consort in British history. The Duke of Edinburgh knew the pressures and responsibilities that came with being a member of the royal family, and wanted to prepare Middleton for it when it was her turn to become Queen.The late royal's advice was revealed in his biography, Philip: The Final Portrait, written by Gyles Brandreth. Philip's advice reads:"If you think the attention is on you personally, you'll end up in trouble. The focus is on your role, what you do, what you support. It's not focused on you as an individual. You're not a celebrity. You represent the royal family."Gyles also wrote that Prince Philip advised Kate not to look directly at the camera, a habit the late Queen Elizabeth followed as well.Royal insiders commended the future queen. One of them mentioned how she followed Prince Philip's advice:"Her composure is extraordinary. She never makes it about herself. That's exactly what Philip drilled into her – and why King Charles and Prince William see her as central to the monarchy's future."Keep reading to learn more about Kate Middleton's poise and personality.Why is Kate Middleton believed to be the perfect future queen?Kate Middleton got married to Prince William, the Prince of Wales, 14 years ago. She has spent more than a decade with the royal family and has learned the way to act as a royal.A royal insider spoke about how Prince Philip saw Kate Middleton's potential as future queen and said:"Philip saw something in Kate early on. He knew she would one day be Queen, and he wanted her to understand the difference between being admired and becoming the story. His message was blunt because he believed bluntness was the only way to prepare her."Another insider source added:"The Duke believed Kate needed armor – not arrogance, not performance, but discipline. That warning was his way of giving it to her, by telling her the spotlight could be dangerous if she ever treated it like celebrity attention."The source also explained why Prince Philip gave Kate such advice. They elaborated:"Kate was guided by the very best. Prince Philip made sure she understood she wasn't there to be a celebrity – she was there to represent the royal family. He told her to stay focused on service, keep her attention on the work, and avoid smiling straight into the camera... He urged her to keep her attention on the role – on duty and dedication – rather than on herself. That's why she's never tried to chase the spotlight or turn any of it into personal fame."The royal source concluded why Kate would be a good queen, even claiming that she resembles Prince Philip in certain ways. They said:"This is exactly why she's seen as the ideal future Queen. She's calm, measured, and never uses her position for self-promotion. That kind of restraint was something the late Duke valued enormously... Kate has a quiet radiance, but she's always understood her place within the royal family. In many ways she mirrors Prince Philip, who stood solidly behind Queen Elizabeth."Prince Philip's guidance helped shape Kate Middleton into the calm and steady royal she is today. By teaching her to focus on duty rather than attention, he prepared her for the responsibility of becoming Queen.