Prince George has expressed his frustration at the relentless battle against discarded waste after litter-picking expeditions at school, the Duke of Cambridge has said.

William, in an interview with BBC Newscast on BBC Sounds, said his eight-year-old son was confused and annoyed when his class returned to the same route the next day to find it was full of litter again.

The duke criticised the space race and space tourism in the 30-minute sit-down chat, saying the world’s greatest minds need to focus on trying to fix the Earth instead.

His comments are being aired the day after Star Trek’s William Shatner made history by becoming the oldest person in space, blasting off in a rocket built by Amazon founder Jeff Bezos’s space travel company Blue Origin.

The duke said: “So George, at school recently, has been doing litter picking.

“I didn’t realise, but talking to him the other day he was already showing that he was getting a bit confused and a bit, sort of, annoyed by the fact they went out litter picking one day and then the very next day they did the same route, same time, and pretty much all the same litter they picked up back again.

Royal visit to Kew
William during a visit to the Royal Botanic Gardens (Ian Vogler/Daily Mirror/PA)

“And I think that, for him, he was trying to understand how and where it all came from.

“He couldn’t understand, he’s like ‘Well, we cleaned this. Why has it not gone away?'”

William said George is “acutely aware” of how the resources he uses affect the planet, such as not overusing water and turning off light switches.

But the duke said he feels bad about giving his children the “burden of that worry”.

William said: “He is acutely aware, more so than the other two at the moment.

“Charlotte is still a little bit young. She’s still not quite sure. And actually Louis just enjoys playing outside the whole time. He lives outside.

“But I think it is slowly dawning on them that these things matter.

“But I think when you’re that young, you just want to have fun and enjoy it.

“I feel bad, I don’t want to give them the burden of that worry.”

The duke, who was speaking ahead of his environmental Earthshot Prize awards on Sunday, expressed concern about the rise in climate anxiety in young people.

“We are seeing a rise in climate anxiety. You know, people, young people now, are growing up where their futures are basically threatened the whole time,” he said.

“It’s very unnerving and it’s very, you know, anxiety-making.”

William also paid tribute to Sir David Attenborough for being a “constant support”.

The TV naturalist is a member of the Earthshot Prize Council.

Sir David Attenborough
Sir David Attenborough is a member of the Earthshot Prize Council (Yui Mok/PA)

“He’s been a constant support through all of this. He’s steered in his gentle David way and we’ve navigated a few things together,” William said.

“And that voice – it’s just legendary, really.”

The duke also admitted he has never watched his uncle the Earl of Wessex’s royal version of It’s A Knockout, but said he understands it had not gone down well.

Edward persuaded the Princess Royal and Duke and Duchess of York to dress up in medieval costumes and perform slapstick feats for the TV game show in 1987.

But it was seen as an embarrassment to the royal family, and, after its finale, Edward stormed out of a press conference when journalists showed little enthusiasm for the pageant.

When Newscast presenter Adam Fleming referred to It’s A Royal Knockout as he introduced a segment he called It’s A Royal Boxset, William replied: “I never watched it but I gather it didn’t go down that well, so, yes, thank you for bringing that up again.”

– BBC Newscast: The Prince William Interview is available on BBC Sounds and BBC 5 Live. It also airs on BBC One on Thursday October 14 at 11.35pm, and on the BBC News Channel and BBC iPlayer.