Prince William explains motivation behind documentary in A Planet for Us All clip

The Duke of Cambridge, who fronts the 90-minute film about his global mission to campaign on behalf of the natural world, is seen feeding a carrot to Tanzanian rhino Deborah in the clip, which you can watch here, before revealing why he feels so passionately about conversation.

"Now I've got George, Charlotte and now Louis, your outlook does change," he says.

"And that's why I had to do something, because I really felt that by the time my children were 20, at the rate poaching was at, there may not be another rhino in the world.

"They are a prehistoric, odd-looking creature but when you get to see their characters and you get to see the family bond they have with their mum, it does make you feel like you're watching a close family unit," he adds. "And the fact that they're under a sort of threat, is really quite sad."

Whilst observing various rhinos in Tanzania, he continues: "People might think, 'That's a big tank, a big hulk of an animal with a big horn,' but they are incredibly vulnerable. They don't have brilliant eyesight and people will take advantage of that, and they want this horn which is effectively nail."

Throughout the documentary, Prince William visits a heavily-guarded secure ivory store, where tusks with a street value of £50 million have been impounded, before speaking at the Illegal Wildlife Trade Conference in London.

The film also covers the Duke's efforts to tackle climate change, following him as he travels across the world to spread the message and meets with leading figures such as Sir David Attenborough.

Prince William recently spoke to Radio Times magazine about the upcoming documentary and his involvement in the climate change debate, saying: "I feel it is my duty, and our collective responsibility to leave out planet in a stronger position for our children."

Prince William: A Planet For Us All airs tonight on ITV at 9pm. Check out what else is on with our TV Guide, or take a look at our new TV shows 2020 page to find out what’s airing this autumn and beyond.