LONDON -- Prince William, his wife, Kate, and Prince Harry will attend a private service at the late Princess Diana's grave on what would have been her 56th birthday.

In a brief statement, Kensington Palace said Wednesday that the July 1 service will be conducted by the Archbishop of Canterbury and attended by Diana's family.

The service comes several weeks before the 20th anniversary of her in August 1997 death in a Paris car crash.

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Diana is buried on the grounds of Althorp estate, her family's ancestral home in the countryside near Northampton in central England.

William and Harry, who were 15 and 12 years old when their mother died, are marking the anniversary by commissioning a statue of Diana that will stand in the public gardens of Kensington Palace in London.

Recently, Harry has spoken out about the difficult time he and his brothers faced when their mother died. The brothers released a video with Catherine saying they didn't discuss their mother's death for a long time, thinking it would be easier to keep their feelings to themselves.

"We've never really talked about losing a mum at such a young age," Prince Harry said to his older brother. "When you speak to other people's families, you think, wow, I don't want them to have to go through the same thing."

William, Harry and Catherine have made mental health awareness their signature charity.

In an interview with "CBS This Morning" in 2016, Harry said he hoped his work on the Invictus Games, a competition of wounded service men and women from around the world that he launched in 2014, would make his mother proud.

"What do you think your mother, Princess Diana, would think about what you've done here for veterans?" co-host Norah O'Donnell asked him.

"I'd hope she'd be incredibly proud," Harry said. "I hope she'd be sitting up there having her own little party and looking down thinking what we've achieved because it's a massive team effort. What we've achieved is absolutely brilliant.

"CBS This Morning" co-host Gayle King spoke with royal biographer Ingrid Weward on the CBS News special, "Princess Diana: Her Life | Her Death | The Truth."

"I keep thinking about her boys today. You know, with the 20th anniversary approaching and all the different things they're going to hear about their mother and their father," King said.



"I think it will be difficult for them, and which is why they've spoken out themselves," Seward said. "When somebody dies… you will do anything to almost keep them alive. And their way of keeping their mother alive is to carry on the work that she started."