You've probably already heard of China's Didi Chuxing. It's the ride-hailing firm best known for driving Uber off China's streets.

It is now also the world's largest ride-hailing app, and with its worth currently at $56bn (£39.4bn), it is also the world's most valuable start-up.

But how much do you know about its enigmatic, low-key founder, Cheng Wei?

Well for a start, he's only 35 years old.

"I was born in 1983," he tells me as we walk around the massive Didi complex on a chilly Beijing morning.

It is his first TV interview with foreign media.

"My entire management team has a lot of people in their 30s," he says. "We are idealistic and can be rash sometimes, but we also bring a lot of surprises."

No-one could accuse Cheng Wei of being rash. Every step of the Didi journey has been well planned.

His first step was to rule the market in China.

His next step, he tells me, is to take over the world: "The Chinese market is of course very important, but today Didi's vision is already going global."