Princess Diana continues to be an enduring force in the lives of her sons, Prince William and Prince Harry.

Despite her death in 1997, Patrick Jephson, Diana’s former private secretary, exclusively tells PEOPLE how the late Princess of Wales is continuing to lead her children.

“If they study Princess Diana’s life carefully — and I hope they often do — William, Harry and their advisers will know that she left them many good examples to follow and also a few important warnings to heed. Public affection and the rich rewards of royalty must be earned with self-sacrifice and service,” says Jephson.

“I’m sure they are grateful that every day she can still guide, comfort and inspire them along the difficult path they were born to follow,” adds the author of Shadows of a Princess: An Intimate Account by Her Private Secretary.

Prince William and Prince Harry were 15 and 12, respectively, when Diana died following a car crash in Paris on Aug. 31, 1997, changing their lives forever.

The brothers grew up sharing a royal life and experience only they can understand, but the Prince of Wales, 43, and Duke of Sussex, 40, are today distanced by a bitter rift that shows no signs of healing.

Fractures exacerbated in 2020 when Prince Harry and Meghan Markle stepped back from royal duties, and the turmoil has played out in the public eye since.

“Things were said that sparked the initial rift, and it’s never healed,” says Diana’s biographer Andrew Morton in this week’s PEOPLE cover story.

In his groundbreaking memoir Spare, Harry describes a tense 2019 confrontation where William criticized Meghan and, according to Harry, physically grabbed him by the collar, knocking him to the floor.

The divide deepened after the couple’s explosive interview in 2021 with Oprah Winfrey, followed by their Netflix docuseries and Prince Harry’s bestselling book — each delivering sharp criticism of Prince William, King Charles, Kate Middleton, Queen Camilla and the institution they serve.

“Some members of my family will never forgive me,” Harry told BBC News in May.

Says Robert Lacey, author of Battle of Brothers: “The rift is very profound and very long-lasting. It will not be changed, in my opinion, until Harry makes a move and apologizes.”

Adds historian Amanda Foreman: “Everyone wants it to happen on their terms, but that’s what makes it impossible.”

Despite the gulf between them, Princess Diana’s sons remain united in a shared vow to honor her memory.

Long before their estrangement, Diana taught William and Harry what that legacy looked like: a new kind of royal life rooted not in pomp but in compassion. Diana didn’t just infuse their lives with normalcy through visits to amusement parks and burger joints; she also took them to shelters for the unhoused and introduced them to her key causes.

Prince William has taken inspiration in his work to help the homeless, while Prince Harry has carried her torch in supporting those affected by AIDS and retraced her steps through Angolan minefields with The HALO Trust.

Tessy Ojo, CEO of The Diana Award — the only charity to bear Princess Diana’s name, and one that her sons now support separately — has witnessed the princes’ commitment firsthand.

“I’ve seen how they watch young people who never met their mother articulate the impact she’s had on them. There is a sense of immense pride: ‘Wow, my mother did that!’ ” Ojo says.

Both brothers have also created home lives grounded in the value of providing their children with a genuinely authentic upbringing — “and that is pure Diana,” says Foreman. Prince William and Prince Harry have also honored their mother by giving their daughters, Princess Charlotte and Princess Lilibet, her name as a middle name.

The Prince of Wales and the Duke of Sussex both speak of her often to their children, and her photograph is displayed throughout their homes.

“The values they are instilling and discussing as families may be their best success,” Foreman says about the King’s sons. “They are both very good role models as parents.”