The Prince of Wales has admitted that green campaigning is “an uphill battle” while wishing Earthshot Prize finalists good luck ahead of Tuesday’s awards ceremony in Singapore.

William, together with Hannah Jones, chief executive of the Earthshot Prize, met all 15 finalists shortlisted for the awards on Tuesday morning at the base of the world famous Supertrees in Gardens by the Bay, to hear more about their projects and how the Earthshot fellowship retreat in Singapore this week has helped them.

While chatting to the Clean our Air finalists, Gunnlaugur Erlendsson, the founder and chief executive of ENSO, a London-based company that makes tyres for electric vehicles that are designed to be more sustainable and reduce pollution, asked William how he had found dragon boat racing on Monday.

Laughing, the prince replied: “Quite competitive, I felt it a bit in the shoulders this morning.”

Hearing how several of the finalists hoped to scale their projects going forwards, William praised them for their work so far, saying: “Campaigning activism is really hard work sometimes, it’s an uphill battle, that’s the point of Earthshot – to elevate the wonderful work you’re all doing. It’s mine and Hannah’s job to scale you up. Good luck to all of you.”

With the Protect and Restore Nature finalists, the prince spoke to Manja Kargbo, founder of the Freetown the Treetown tree-preservation project in Sierra Leone, a “pay as you plant” scheme for local communities.

He asked her: “Has this week and the fellowship been helpful, useful?”

Ms Kargbo told him: “It has been an amazing week, with so much energy and engagement with my cohort.”

William also spoke with Nidhi Pant of S4S Technologies based in India, one of the Build A Waste Free World finalists.

Her project combats food waste, rural poverty and gender inequality by helping smallholder female farmers preserve and market surplus produce, including misshapen vegetables.

He told Ms Pant: “It’s so important. The amount of conversations we have as a family – picking up a carrot with a funny shape and asking why it can’t be sold – it’s mad.”

In the Revive our Oceans category, William also heard from Serge Raemaekers, the co-founder of South African-based project, Abalobi, which aims to protect small-scale fishing communities and provide customers with more information about the source of seafood, via an app which connects fishers with a digital marketplace where they can register their catches and log where fish come from.

Wishing all the groups good luck again, before a final group photo, William told them: “All of you, whether you win or not, you’re now part of the Earthshot family.”

The awards are aimed at recognising solutions to “repair” the planet, and will see five category winners presented with £1 million each to scale up their environmental ideas.

After meeting the prince, Mr Erlendsson said William told him his category was “one of the hardest to judge”.

He told William about the Earthshot Prize’s fellowship retreat which included being introduced to Jacinda Ardern and a team from Bloomberg.

He added: “We had a brief discussion of course about the next days and he said, in particular, the third category was very difficult to judge, he said basically our category was one of the hardest to judge.

“Nobody knows who was going to win the award, but winning the award or the prize isn’t really the key thing, it’s really to be part of the community and to be a finalist, everyone gets the same treatment.”

Ms Kargbo said she was “really excited” about the awards and that she was “already a winner”.

Orr Yarkoni, chief executive of UK-based Colorifix, which uses DNA sequencing and nature’s own colours to create sustainable dyes that reduce the fashion industry’s use of water and harmful chemicals, said meeting the prince “was wonderful”.

He said: “He wanted to hear about how long we’ve been going on this journey and what actually got us started into it, which was our passion for water quality.”

During the first two days of his trip to Singapore, William was greeted with cheers as he arrived at Jewel, a nature-themed complex at Changi Airport.

He later won a dragon boat race on the Marina Reservoir against a backdrop of Singapore’s most famous landmarks, and met the president of Singapore, Tharman Shanmugaratnam, and the prime minister of Singapore, Lee Hsien Loong, at the Istana.

He also attended a United for Wildlife summit, aimed at tackling the illegal trade in animal parts, where he gave a speech.