Prince William’s poignant ITV documentary showed Prince Harry is “blinded by sour grapes” as it proved him wrong, according to a royal expert.

Last night, the first part of the Prince of Waleses’ new show Prince William : We Can End Homelessness was broadcast on TV, exploring the first year of his Homewards initiative, which aims to develop a blueprint for eradicating homelessness in all its forms, “making it rare, brief and unrepeated”.

The documentary showed William mirroring the work of his late mother Princess Diana, who first highlighted the plight of homelessness. He was seen volunteering at homelessness shelter The Passage, convening meetings with charities and landlords and inviting former rough sleeper Wayne to chat with him at Windsor Castle.

Royal expert and historian Dr Tessa Dunlop says the documentary showed William in a whole new light – and not exactly one that was described by his estranged brother Harry. She explained to the Mirror : “Bright blue eyes, open-necked shirt, hands casually crossed on his knee, this was Prince William as we have never seen him before.

“Charming, charismatic and kind, a man on a mission to end homelessness, a prince with the capacity to convince the suits in society and simultaneously get down with the kids.

” ITV ‘s ‘Prince William, Together We Can End Homelessness’ wasn’t just moving television, it reframed the Prince of Wales as a future ‘King of hearts’. In the opening of his memoir Spare, Harry insisted that William with his ‘alarming baldness’ was losing his ‘famous resemblance to Mummy.’ It was fading apparently.

“The Duke of Sussex, blinded by his own sibling-sour grapes, couldn’t be more wrong. Last night, William channelled Diana. The same big-eyed stare, the same capacity to make the unseen in society feel seen, the same sincerity; as William readily owned, he had ‘taken guidance from what my mother did’.

“As a charity boss casually observed, William isn’t just a celebrity, he is a ‘super celebrity’ and his capacity to work that status was there for all to see. When else would an issue like homelessness get two consecutive slots on prime-time TV?”

“As for questions about the prince owning too many palaces to be a credible homelessness champion – he faced down that accusation by front-lining Windsor Castle mid-documentary to underscore his status as the man who can. Former street sleeper Wayne didn’t care, he just wanted a platform to tell his story.”

Tessa added that the spirit of the late Diana was ever present throughout the first part of the documentary – and she believes that despite his highly privileged position, he is using it in the best possible way.

She explained: “Over-shadowed recently by the King and Kate’s cancer scares, and long considered the less accessible of his sibling duo, last night served to set the record straight. William has got what it takes to deliver a compassionate kingship and simultaneously forefront Diana.

“She was ever present throughout the documentary, William openly admitting that it was thanks to her early influence he understood what went on outside palace walls. From his privileged position, he gets it.

“As he said himself ‘why else would I be here if I am not using this position properly?’ Why indeed? I shed a tear, and surely I can’t have been the only one. Let’s face it, compared with those sleeping on the streets, we all live like princes. It’s ironic that it took a real prince to make that point.”

The second part of the documentary will be broadcast tonight at 9pm on ITV1 and ITVX, STV and STV Player.