His Majesty’s son is seen as a young boy alongside his father

Prince Harry makes a brief cameo in King Charles’s new documentary, “Finding Harmony: A King’s Vision”.

The footage features a short clip of the future Duke of Sussex fly fishing with his father as a young boy.

Prince William makes two appearances in the upcoming production.

One shows the future King as a boy, lying down in the grass with Charles, and another shows him tending to some cows when William was in his 20s.

Harry made a cameo in his father’s documentary | GETTY

His Majesty’s new Prime Video documentary looks back at the King’s philosophy and lifelong commitment to green issues.

The 90-minute film shows His Majesty warning the climate crisis is “rapidly going backwards” with mankind “actually destroying our means to survival”.

He hopes there will be greater awareness of the issue, with a “need to bring things back together again”.

Actress Kate Winslet narrates the film and describes how the King, as Prince of Wales, emerged as a key figure on the environment, making regular keynote speeches, despite “cries from some that he should take a back seat”.

William makes a couple of appearances in the documentary

 | PA

The actress was among a number of A-list celebrities who attended the premiere of the documentary.

Ms Winslet described the documentary as a “special” and “important” work as she lifted the curtain on the event.

She gave some insight into the production, telling guests before the viewing: “Harmony is a beautiful theory that invites us to see ourselves as a part of nature – not apart from it – and to tackle the world’s climate challenges using an interconnected, nature-first approach.

“You are about to see just how this theory has already been put into practice around the world, in so many inspirational ways, across a multitude of different cultures and sometimes for centuries.”

Finding Harmony: A King’s Vision tells the story of His Majesty’s lifelong dedication to environmentalism

 | PRIME VIDEO

The film took six months to complete, but has been “a lifetime in the making” for Charles.

In new footage, the King explained: “I just felt this was the approach that I was going to stick to. A course I set, and I wasn’t going to be diverted from.”

Charles previously warned that the approach to climate change is “rapidly going backwards,” as the monarch shared his concerns.

He said: “People don’t seem to understand it’s not just climate that’s the problem – it’s also biodiversity loss, so we’re actually destroying our means of survival, all the time.”

Kate Winslet narrated the King’s documentary | PA

A spokesman for the King said the film was “not a conventional royal documentary”.

“There are no golden carriages here; no glittering crowns or crimson robes.

“Instead, this is a deeply personal exploration of ideas that have shaped His Majesty’s life and work: the interconnectedness of all things, the wisdom of traditional knowledge, and the belief that we can build a future that works in partnership with nature rather than against it,” the spokesman added.

Finding Harmony: A King’s Vision will be released on Prime Video on February 6 in more than 240 countries and territories worldwide.