Prince of Wales says Kate ‘is doing really well’ as Earthshot Prize event closes

He trod the award ceremony’s green, not red, carpet in a second-hand double-breasted Prince of Wales check jacket, from a London Vintage store – in keeping with the sustainable fashion ethos guests were asked to follow.

And he wore white sustainable trainers from Purified Footwear – which produces plastic free, biodegradable sneakers.

The future king praised the support he has received from his wife for his ambitious initiative rewarding environmental entrepreneurs with £1 million to scale-up their innovative ideas to “repair” the planet.

Kate is slowly returning to public duties after completing a course of cancer treatment, and ahead of the ceremony William said he hoped she would be watching and “cheering me on”.

The royal family will be taking part in national events marking Armistice Day this weekend, and Kate is expected to attend the Remembrance Sunday service at the Cenotaph with senior members of the monarchy.

In an interview with the BBC, the prince was asked about his wife and replied: “She’s doing really well thanks. And i hopefully she is watching tonight. So cheering me on. She’s been…amazing…this whole year. I know she will be really keen to see tonight be a success.”

William told the awards ceremony held in an eco-dome with the audience, including the prince, wearing bracelets that flashed different colours at key moments: “…The Earthshot Prize isn’t just a celebration of winners.

“It’s a collaborative movement for change. And I now invite you to join the movement for climate innovation that’s happening around the world.

“Because that’s why we’re here.

“To champion the dreamers, the thinkers and the innovators from every walk of life, who share an ambition to build a better, more sustainable world.

“We’ll do everything we can to support them and help speed their solutions to scale. Because when they succeed, we all succeed. When they thrive, we all thrive.”

Five category winners who will each receive a £1 million to scale up their ideas to “repair” the planet were announced by a host of stars including models Heidi Klum and Winnie Harlow.

Klum, who named the Fix our climate category winner, said: “We all need to think about climate change and it’s great to spread the word and shine a light on these amazing organisations and what they do.

“I’ve learnt so many things since I’ve been here, I’m in the fashion industry so I know it’s so important to turn away from fast fashion, re-wear your clothes. Princess Kate always re-wears her clothes.”

In his BBC interview, William said he hoped his children were “proud” of the work of his Earthshot Prize – a 10-year project to boost optimism about the planet’s future – and said his family was eco-conscious, minimising their effect on the environment.

The heir to the throne said they recycle, reduce their water use and turn off the lights when leaving their home.

Asked about what he did at home to help protect the planet, the prince replied: “Every family tries to do what they can to sort of help with the environment.

“We go through all the basics of recycling and making sure we minimise water use and turning off lights when we leave the house and stuff like that… Which is sensible in what we do around the environment.

“And I think every family has these conversations. You just try to do what you can.”

The prince went on to say: “The Earthshot Prize has got to be a bit more global than that. We are trying to do big-scale ambition and big-scale business to tackle some of the solutions.”

The winner of the Fix our climate category was Advanced Thermovoltaic Systems, which has developed technology to convert waste heat into energy, while the High Ambition Coalition for Nature and People, an alliance of 119 countries aiming to protect 30% of land and oceans, was named winner of Revive our oceans.

Keep It Cool, a Kenyan project helping farmers and fishers refrigerate their produce won Build a waste free world and the Altyn Dala Conservation Initiative, which has helped save the endangered Saiga antelope from extinction in Kazakhstan, won the Protect and Restore Nature category.

Green Africa Youth Organisation, a Ghana-based group working to cut greenhouse gas emissions and particle pollution, won the Clean our air category.

After the presentation, William said to the winners: “It was so close. All the finalists were so close. There were the little things that just got it over the line.”

He told the Green Africa Youth Organisation: “Having you guys living in Africa is such a big deal. Timing is crucial.

“This will give you power, strength and, guys, we will back you. I hope you felt the energy in the room. You’ve got hard yards ahead but we will support you.”