Martin Clunes has returned to Africa to make A Lion Called Mugie, a documentary about saving an orphaned lion cub.

Martin, now a patron of the Born Free Foundation, made his first animal-themed documentary in 1998 about an elephant called Nina, rescued by conservationist Tony Fitzjohn, who worked with wildlife conservationist George Adamson for decades.

Doc Martin star Martin has remained friends with Tony and returned to Kenya to help rescue an orphaned lion cub, Mugie, and rebuild George Adamson’s camp in the Kora National Reserve. The camp was burnt down in 1989 after George was murdered by Somali bandits. Mugie would be its first lion for 25 years, so it was a momentous occasion.

The cub had been washed up on a riverbank 140 miles away and Tony and Martin went to collect him.

“He was labrador-sized and as sweet, cuddly and playful as you’d expect, although even then you could see those paws were pretty big,” says Martin.

Back at Kora, they began training the orphaned lion to be wild.

“You do that just by walking with them,” Martin told the Daily Express. “Cats have an instinct to chase squirrels, for example. They learn to get downwind of their prey – all that stuff is in their DNA. Tony is there to make sure they’re safe from other predators.”

Martin admits he was nervous on the day he took a walk with Mugie. “He was full of beans – he was just looking at me. We were all mindful of it, but I did get to have a walk,” he says.

But time is running out for the lions. Poaching and destruction of the natural habitat are sounding the death knell for much of Africa’s wildlife and it is thought Kenya’s population of about 2,000 lions faces extinction in less than 20 years. The way forward is to create habitats to keep lions in and poachers, predators and farmers out.

“It’s a sad reality, but it’s got to be done,” Martin says. “They’re not like walls. They’re huge areas of land that will protect farmers’ livestock from lions.”

One hopeful sign, adds Martin, is Prince William’s commitment to conservation. Since 2005, the Duke of Cambridge has been patron of conservation charity Tusk Trust and last month unveiled his own charity, United For Wildlife.

“It’s so fantastic that Prince William has championed African wildlife,” says Martin. “He’s putting his back into it – and one thing the royal family is brilliant at is getting people to cough up.”

Martin Clunes and a Lion Called Mugie, ITV1, Friday, April 4