Where did the idea for show South African Adventure originate?

The idea was to go to countries I’ve been to before to get to know the place and the people better, and for [viewers] to be able to do all the things we do. You mention Africa and the impression is that it is dangerous, but for South Africa that stuff happened 20 years ago.

Is an element of that past still visible?

The thing about Johannesburg is as a foreigner there are parts you shouldn’t go to, but that’s the same in any city. Washington DC is the gun and stab capital of the world. Now you can go to Soweto – which was a nightmare 20 years ago because of apartheid and the uprisings – and do a bicycle tour where they show you Mandela’s house and where the Zulu uprising and student massacre were. It’s very humbling.

Where else did you go on the trip?

We went down the coast, on the sardine hunt and we came across this pod of dolphins. I ended up jumping in the water with 600 common dolphins and swimming with them. There is some of the best surfing in the world in Durban, too, but you do have to dodge the great white sharks, which you can see behind you. We went cage diving with the great whites, in this cage that feels more like a shopping trolley. These things come up with their mouths open and hit the cage. You are just half a foot away thinking, “I am not sure about this.”

Where else did your travels take you?

We went diamond mining along the west coast, where people aren’t allowed to walk on the beaches because there are diamonds. You go diving with this breathing apparatus connected to the boat down to the sea bed and hoover them up from there. That whole bit of coast between the tip of South Africa and Namibia is full of diamonds. 

What surprised you the most?

The top of Drakensberg, mountains that are home to the second-highest waterfall in the world, Tugela Falls. We pitched our tents in snowdrifts and it was -7°C – I wasn’t expecting that. I thought deserts, animals and wildlife, not freezing cold. It is a much more diverse country than I thought. The people are incredibly friendly and want to entertain. It is an incredibly warm and welcoming place to be.

Do you always plan to end these trips with a mass ride, like this one’s 300-strong convoy into Cape Town?

I am such a bike enthusiast and there are so many others around the world. It doesn’t take much to organise, just a couple of phone calls to a bike club and the odd radio station, then suddenly you have people following. The ride in to Cape Town is incredible, there is nowhere in the world where you can go swim with penguins one minute and then the next sit on some beautiful restaurant terrace in the wine regions.

Which moment stood out the most?

Adrenaline sports are a calculated risk. We went up a road called the Sani Pass, one of the top five biking roads in the world. We got two thirds of the way up to find it had turned to sheet ice. The bike was slipping down, so we got this guy in a four-wheel-drive to give us some help. On this last corner the wheels started spinning and we skidded backwards. At that point I thought, “Shit, we’re going over the cliff.” I had the door open so I could bail out if necessary. Whether it was the guy’s skill or luck, we came to a halt. Once it’s over you all look at each other and go, “Fucking hell.”

What do the wife and family think about you taking these risks? 

I never tell them what I am going to be doing, only what I have done. 

You’ve got some rides planned in Australia next month, too …

Every year I do a couple of motorcycle tours – from Cape Town to Victoria Falls and then through Malawi back to Johannesburg. And the other is a tour of Oz, one from the Blue Mountains behind Sydney into the outback and one round Tasmania.

So why choose London as your base?

I came here at 18 and made it my home. It is a lovely city to live in. It has a bit of everything: culture, arts, theatre. It’s the perfect place to live!

Are you still working on plans for The Long Way Up with Ewan McGregor from South America to Alaska?

The third one was always on the cards but as and when we’re not sure. Ewan’s busy acting, which he loves, and it would take seven months to do [the trip] so finding the space in the schedule is hard. We’re not too bothered, though, we have plenty of time to do it.

Charley Boorman’s South African Adventure begins January 9, 8pm, on Channel Five