The King walked the blue carpet as he attended the premiere of Sir David Attenborough's new documentary at London's Royal Festival Hall.
Rounding off a busy day of engagements, which coincided with the second anniversary of his coronation, lifelong environmentalist Charles, 76, was reunited with Sir David, 98, to watch the beloved natural history TV presenter's new film, Ocean with David Attenborough.
The pair chatted animatedly together as they met before the film, in which the broadcaster describes the oceans as "the greatest asset against climate change" before adding a stark warning.
"Today, it is in such poor health I would find it hard not to lose hope were it not for the most remarkable discovery of all," he said.
"If we save the sea, we save our world. After a lifetime of filming our planet, I'm sure nothing is more important."
HELLO! understands the Prince of Wales privately attended a screening of the documentary earlier on Tuesday before the star-studded premiere.
The King, who is patron of the Marine Biological Association, has advocated for protecting the environment and sustainability, including in the oceans, for more than five decades.
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© Alan Chapman/Dave Benett/WireImaVIP guest
The King, dressed smartly in a tuxedo, walked the blue carpet at the Royal Festival Hall before meeting guests.
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© Getty ImagesA shared cause
Meeting with Sir David and his daughter Susan ahead of the premiere, Charles said he was "so glad" the broadcaster was involved with the film and that it was "always a pleasure" to see him.
The King asked the veteran broadcaster about his 99th birthday, which Sir David confirmed was on Thursday, the day of the film's release.
Charles remarked in response: "I can't believe it."
His Majesty has met Sir David several times before as his work as an ambassador for the natural world and his passion for the planet overlap with the King's own work to promote sustainability and protect nature and the oceans.
On 19 February 1970, Charles, as Prince of Wales, first marked the "growing menace" of oil and plastic pollution in the sea, during a speech at the 'Countryside In 1970' conference.
Since then, the monarch has continued to champion the importance of the ocean, with his niece, Princess Eugenie, also sharing the trailer for the documentary on Instagram Stories on Tuesday.
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© Getty Images"Most important story"
The King meeting actor Theo James upon arrival.
Toby Nowlan, from Silverback Films – the movie's producer and director, said it was Sir David’s "most important story" and came at a crucial moment for global environmental efforts.
He told reporters: "A lot of people got together and said we need to make a seminal film to enact change for our ocean, to be released now – halfway through the United Nations' decade of the ocean, this year, the year of the ocean – in time for the United Nations Oceans conference in June in Nice.
"So the idea was basically to find the greatest authority on storytelling and the greatest authority in wildlife filmmaking to front this piece."
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© Mike Marsland/WireImageStar-studded arrivals
A whole host of celebrities were also in attendance at the premiere, including Geri Halliwell-Horner, Ayda Field and Cara Delevingne.
Former Spice Girl, Geri, donned a shirt dress in her signature white hue with metallic shoes and a red handbag.
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© Getty Images for National GeograAyda Field
The American film and TV actress looked gorgeous in green.
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© Getty Images for National GeograPoppy and Cara Delevingne
Sisters Poppy and Cara Delevingne appeared on the blue carpet together.
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© Alan Chapman/Dave Benett/WireImaPenny Lancaster
The Loose Women star looked elegant in an embellished number as she was accompanied by her son, Alastair Stewart.
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© Getty Images for National GeograSofia Wellesley and James Blunt
James Blunt's wife Sofia opted for an apt ocean-blue one-shoulder dress.
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© Alan Chapman/Dave Benett/WireImaFelicity Jones and Charles Guard
Actress Felicity Jones stepped out with her director husband, Charles Guard.
Ocean with David Attenborough airs Sunday 8 June at 8pm on National Geographic and streams the same day on Disney+.
