King addresses his own mortality in 'deeply personal' new film as Prince Harry makes surprise cameo

King Charles has addressed his own mortality in a new documentary film that focuses on his greatest passion and life's work: protecting the natural world.

The 77-year-old, who was diagnosed with cancer in 2024 and is still undergoing treatment, said he hoped humanity would realise it is part of nature before he "shuffles off this mortal coil".

The premier of Finding Harmony: A King's Vision was held at Windsor Castle on Wednesday (Thursday morning in Australia), believed to be the first time such an event has been held at a royal residence.

The King and Queen Camilla, along with the Duchess of Edinburgh, were among the high-profile guests at the premier.

And in a surprise moment, the King's estranged son Prince Harry appears briefly in the 90-minute film.

King Charles has been speaking about the need to protect the environment since the 1970s.

The film, which will be released globally on Amazon Prime on February 6, focuses on the monarch's work he has done on the environment and sustainability for decades.

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A spokesperson for the King called the documentary a "deeply personal exploration of ideas that have shaped His Majesty's life and work".

In it, the King admits frustration and the lack of progress being done to curb the impact of humans on the natural world.

"It's rapidly going backwards," the King says. "I've said that for the last 40 years, but anyway, there we are."

But, then addressing the limitations he has as a constitutional monarch when it comes to politics, Charles says: "So, that's why I get a bit, anyway… I can only do what I can do, which is not very much. Aaah, anyway…"

Watching some of his early speeches on the issue of the environment, the King says he was considered by many to be "completely bonkers".

The narrator, actress Kate Winslet, says the King's ideas where once considered "crazy" but they "now seems like common sense".

The King is asked whether he is "worried about the state of the world".

He replies: "Of course. That's been my main motivation for a long, long time, and you can see what's happening. But I mean the underlying principles behind what I call Harmony, I think we need to follow, if we're going to somehow ensure that this poor old planet can support so many."

Looking up to the sky, and space, the King adds: "It's unlikely there's anywhere else".

At the end of the film, the King says: "It all boils down to the fact that we are actually nature ourselves, we are a part of it, not apart from it, which is really how things are being presented for so long.

"Maybe, by the time I shuffle off this mortal coil, there might be a little more awareness... of the need to bring things back together again."

The phrase "shuffle off this mortal coil" is taken from William Shakespeare's Hamlet.

In more modern contexts, the phrase has become another way to say "to die".

Another scene in the film shows the King walking through his Highgrove gardens, referring to trees he planted years ago that he thought he would "never live to see" them grow so high.

"The beeches I'd planted right at the beginning – and I can't believe how much they've grown, if you think what it was like," the King says.

"I thought I'd never live to see it. The fact that I have, is praise be to God, frankly."

Prince Harry's surprise cameo

There was a brief appearance by the Duke of Sussex in his father's new project.

He is seen in archival footage taken at Balmoral, in the Scottish Highlands, with Charles showing his youngest son how to fish.

In September last year, King Charles met with Prince Harry inside Clarence House in what was their first face to face gathering in 19 months.

Prince William also features throughout, including in old vision taken at Highgrove, and later with his children Prince George, Princess Charlotte and Prince Louis at the coronation in 2023.

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