The Prince of Wales arrived on a special electric bus to deliver a keynote speech highlighting the success of his Earthshot Prize.

William, 44, was joined by environmentalist Robert Irwin and two young campaigners on the specially-branded route '2030' double decker - the 3,000th to enter the Transport for London fleet - on the short journey to London's historic Guildhall, where his Earthshot Prize Impact Assembly in London was being held.

The awards - designed to highlight and scale up some of the world's most innovative solutions to the climate change and global environmental crisis - were started in 2020 to run for ten years and hand out £5 million in prize money to winners each year, as well as providing them with mentoring and support.

Today's event brought together finalists and winners, as well as global leaders from business and philanthropy, to celebrate solutions and announce a series of exciting new initiatives.

In his speech William said he had always hoped his Earthshot Prize would 'show the world evidence of progress - progress towards what felt like immense climate and nature goals.'

'Today we have more than belief. We now have proof. Solutions are working. Capital is moving. Policy is shifting. Partnerships are forming,' he said.

'Our finalists are calling. Progress is starting to build on itself. This is why I feel more optimistic than ever.

'Not because the challenge is smaller than it was, not because the science is less urgent, but because the proof is stronger than ever before. '

He said that since the start of the awards they have supported 75 Finalists and awarded £25 million in prize funds as well as helping to avoid or capture 18 million tonnes of carbon dioxide, protecting and restoring 1.4 million square kilometres of land, ocean and coastline, saving 21 million tonnes of water and removing, upcycling or avoiding almost half a million tonnes of waste.

'Those numbers matter. They mean individual lives and entire systems are changing as our Finalists achieve big things,' he said.

Highlighting the fact that the awards are now more than halfway through their decade of change, with India the next venue later this year, he said: 'One day people will look back at this decade and ask: when the evidence was clear, what did we do with it? 

'When we saw forests being restored, did we help restoration spread? When we saw clean air policies working, did we help other cities follow? When we saw the energy systems transform, did we fully commit? When we saw communities on the front-line becoming leaders in resilience, did we stand beside them?

'That is the responsibility of this moment.

'And it is this story that matters, not just the problems we face, but the collective response to tackle them.

'The challenge can still feel immense but the proof is now in front of us. And history will ask what we did with it.'

Young campaigner Pranav Sharma, 19, said they discussed a huge range of issues with the future king on their 20 minute bus journey to the awards, saying he was impressed by his 'determination for optimism in a time where everyone has so much to deal with'.

Clover Hogan, 27, added: 'It was amazing. I mean, it was very down to earth conversation. I think we all come from really different backgrounds and life experiences, yet we're united by the shared love, nature, the planet, and people, and so it was just really fun conversation.

'One of the things that we touched on is how overwhelming climate change can feel as an issue.

'I watched documentaries when I was 11. In many ways, they depicted the worst aspects of humanity. I remember….feeling, frankly, terrified about the state of the world and where we were headed.

'And yet they also shone a spotlight on these incredible groups of people who were doing everything in their power and overcoming incredible adversity to solve these issues. And so for me, that is really a testament to the power of storytelling as well.

'We're up against a lot of issues. And yet there are countless people throughout the world who are already leading the way.

'I think Earthshot is an incredible platform for a number of those solutions. Something that a lot of people don't know is that we already have all the solutions we need to not just slow emissions, but actively reverse them, bring back nature, and build up communities.

'[Prince William's] role is so important. He can access audiences that many of us within the climate movement potentially can't. And I think it signals something very important in terms of the royals caring about climate, sustainability, caring about people and the direction that we want this country to go in. And that was something that we spoke about really frankly, you know, the fact that we need political support, right?

'We need a public mandate and we need those we elect into power to actually get behind this and not just make into your false parameters, but to actually do what they say they want to do.'