London, UK - Are Prince Harry and Prince William ready to reconcile? According to one royal expert, a reunion is still a ways away for the estranged brothers.

In the upcoming documentary Prince William: We Can End Homelessness, the heir to the British throne spoke publicly about his brother for the first time in six years.

On Monday, royal author and journalist Mr. Dampier told The Sun that the late Princess Diana would be "devastated" that Harry did not support his brother on this important project.

After all, it was always important to the princess to show her sons that not everyone has lives as privileged as theirs.

"She was determined to show them that not everybody lived in palaces, and not everybody was born with a silver spoon in their mouth," Dampier said.

"Diana let them sleep rough overnight when they were younger, to show them what it was actually like."

But even though Harry wasn't involved in the documentary, William's decision to name-drop him might be an "olive branch" to his estranged brother.

However, Dampier is not convinced that a reconciliation is on the way.

"It's just a rather sad indication of the fact that something which they could have worked together on, and something which they both experienced at a young age, they're no longer doing," he said.

"It's just left William on his own, and Harry's not joining in, so I don't see this as an olive branch."

When asked why the future king still decided to name Harry, the expert explained that William could not simply leave him out of the story.

"He couldn't not mention Harry, because he's in all the photographs, and he's in all the films when they went with Diana."

Still, the pair did give fans hope of a reunion when William publicly wished Harry a happy 40th birthday with a post shared on the Kensington Palace social media pages.