New Althorp memorial for Princess Diana

Princess Diana’s brother Charles Spencer is working on a memorial to her at his Althorp estate.

Diana, who died in a car crash in 1997, is buried on a small island on the grounds of the 50-acre estate and although the grave was previously left unmarked, he is planning a physical memorial as part of a revamp of the grounds, which will be completed by her 20th anniversary next August.

Charles, who is the Ninth Earl Spencer, told PEOPLE: “Before, we left the grave unmarked because the family knew where it was. But now we’re going to have a memorial to Diana.”

He is also having forget-me-nots and rhododendrons planted on the island for his sister.

Charles said: “Forget-me-nots were Diana’s favourite flower. I still remember giving her some when we were children. When I was six, I gave her a white pot of blue forget-me-nots.

“Rhododendrons were also chosen because they were the flower at Sandringham,” where the Spencer family lived before moving to Althorp.

Charles’ wife Karen said: “For my husband, Diana was the person he was closest to his whole life, so it’s a big void for him. That loss is still palpable in my husband.”

Karen founded the Whole Child charity in 2004 and Charles says her philanthropy reminds him of his sister.

He explained: “Like Diana, she gets her hands dirty with causes that other people might quickly walk away from. What my sister did for people with HIV/AIDS, the homeless and those suffering from leprosy, Karen is doing: fighting for orphans and abandoned kids.”