It was a pact the Duke of Sussex and the Prince of Wales made together in their younger days, but it ended, Harry said, in heartbreak.
The duke, in his Netflix documentary, said he and William promised never to trade or leak stories or brief against one another after witnessing the fallout of such actions in their father’s office.
Yet in episode four of the Harry & Meghan docuseries, Harry accused his brother’s team at Kensington Palace of doing just that.
“William and I both saw what happened in our dad’s office and we made an agreement that we would never let that happen to our office,” he said.
He added: “I would far rather get destroyed in the press than play along with this game or this business of trading, and to see my brother’s office copy the very same thing that we promised the two of us would never ever do, that was heart-breaking.”
The duke’s allegations against his brother in the final three episodes included damaging claims he was left terrified after William screamed and shouted at him in front of the Queen during the Sandringham summit in 2020, and that the Palace “lied to protect” William over bullying accusations by issuing a joint statement without Harry’s permission.
The claims, and Harry’s decision to make them public, are being seen as evidence the fraught relationship between William – now heir to the throne – and Harry – once the spare to the heir but now no longer a working royal – will never be resolved.
When younger, William and Harry’s bond appeared unbreakable, and they were united in their experience of a royal childhood and the trauma of losing their mother.
Harry said when he was 21: “It’s amazing how close we’ve become. I mean, ever since our mother died, obviously we were close, but he is the one person on this earth who I can actually really … we can talk about anything.
“We understand each other and we give each other support.”
The duke stopped short of attacking his older brother in his two-hour sit-down interview with Oprah Winfrey in 2021.
“The relationship is space at the moment,” Harry said. “And time heals all things, hopefully.”
He added: “I love William to bits, he’s my brother, we’ve been through hell together, we have a shared experience, but we were on different paths.”
According to the Finding Freedom biography, their rift stretched back to before the royal wedding when Harry was angered by what he perceived as his brother’s “snobbish” attitude to Meghan, after William questioned whether he should rush into things with the ex-Suits star.
Broadcaster Tom Bradby, a friend of the Sussexes who interviewed them for a documentary about their Africa tour, also wrote about the rift: “The fallout began at the time of the wedding in 2018.
“Really damaging things were said and done.
“The atmosphere soured hard and early, but few meaningful attempts were made by anyone to heal the wounds.”
He added: “There is no doubt Harry and Meghan feel they have been driven out.”
In the Netflix documentary, Harry said the Palace “lied to protect my brother” when it issued a joint statement in both their names on the day of the Sandringham summit without his permission, denying a story that William had bullied him out of the royal family.
The Sussexes went on to step down as senior working royals and move to California.
But Robert Lacey, author of Battle Of Brothers: William, Harry And The Inside Story Of A Family In Turmoil, said there were problems much earlier than the royal wedding, including in 2005 when Harry was condemned for dressing up as a Nazi for a “colonials and natives” party.
Harry was accompanied by William when he chose the costume in a fancy dress shop, but there was no criticism of his older brother in the press, with Harry left struck by his own role as “the monarchy’s institutional scapegoat”.
Post-Megxit, in their Oprah sit-down, the Sussexes accused the royal family of racism, the institution of not helping Meghan when she had suicidal thoughts and Kate of making Meghan cry.
William was said to be furious that private family matters were brought into the public domain, and insisted, in response to a question from a reporter while on an engagement, that the royal family was not racist.
In the summer of 2021, William and Harry came together to unveil a statue they commissioned of their mother on what would have been her 60th birthday – but although their appearance side by side appeared relaxed and cordial, it was brief, with Harry departing from Kensington Palace soon after.
During the Queen’s Platinum Jubilee and then the aftermath of Elizabeth II’s death, the brothers appeared to spend little time together, although Harry, Meghan, William and Kate did appear together to view flowers and greet well-wishers at Windsor who gathered to pay their respects to the late monarch.
Questions will now be raised as to whether Harry and Meghan will be invited to attend the King’s coronation in May, or whether their relationship with the royal family – and William in particular – has been damaged too far.