The heartbreaking promise Prince William and Prince Harry made to Princess Diana before her death

The promise has been revealed in a new book

Princess Diana Prince Harry Prince William
(Image credit: Photo by Julian Parker/UK Press via Getty Images)

Prince William and Prince Harry both made a promise to their mother to always remain "best friends" and "never let anyone come between them" a new book reveals.

Princess Diana once made Prince William and Prince Harry "promise to be best friends" forever, according to a psychic friend of hers. 

Simone Simmons used to meet with Princess Diana before her tragic death in 1997, and has since revealed the one wish she made her sons promise to keep.

Simone's quotes feature in Robert Lacey's updated version of his book, Battle of Brothers, in which she claims Diana said, "You must promise me that you will always be each other’s best friends."

"And never let anyone come between you."

Of course that promise is even more devastating now that the brothers are arguably worlds apart following Prince Harry's decision to 'step back' as senior members of the royal family. 

After admitting they were on "different paths," Prince William and Prince Harry are now embroiled in a full-scale feud which royal experts say has a "long way to go" before being healed.

Princess Diana Prince Harry Prince William

(Image credit: Photo by Terry Fincher/Getty Images)

In his book, Robert Lacey goes on to recall another of Simone's memories.

"Both boys promised they would keep to that. They high-fived each other and gave their mother a big cuddle."

The close bond she talks of is a far cry from the Duke of Cambridge and the Duke of Sussex's current relationship, which is said to be tense after the Duke launched a scathing attack on the institution in a bombshell interview with Oprah Winfrey.

Despite their differences, the boys are expected to put on a "good show" in a few weeks as they finally unveil a memorial statue for Princess Diana in the Sunken Garden at Buckingham Palace. 

It will be the first time the brothers have seen each other since Prince Philip's funeral.

Georgia Farquharson

Georgia writes across Woman & Home and Good to Know and specialises in all things royal. Previously labelled the "Queen of the royals," Georgia knows the whose who and what's what when it comes to the monarchy. When she's not eagerly following the royal family, Georgia enjoys shopping and self-care. She lives with this motto in mind; "if your dreams don't scare you, they aren't big enough."