“I grew the business from just me up to 12,000 people. From no turnover up to £2.4bn.” When Caudwell sold up in 2006, he made £1.5bn. 

“My life changed because suddenly I had nobody to do anything for me,” he says. “I’d probably never switched a computer on in my life. It was absolutely my identity. It was me, everything I was.” He no longer had an email address.

A decade and a half later, he has turned his sights to property development. Caudwell Properties is redeveloping Audley Square, an eight-storey block of 29 apartments around the corner from his Mayfair home. The homes will be “super-super-prime,” Caudwell says. 

After building a fortune on technology, does property development not seem somewhat pedestrian? “Massively so, but I wanted pedestrian because I was stressed out to the eyeballs every single day. By the time I sold the business I was burnt out.”

He hesitates. “Maybe burnt out is the wrong word. I could have carried on for 20 years if I had to. But I didn’t want to. I’d achieved everything I wanted to achieve and I was fed up of the monster stresses.”

Audley Square is a bet on a prime central London market bounce. But prices have fallen by 20pc since 2014 and travel restrictions wiped out the flow of international buyers that account for half the market. Caudwell thinks he has timed it perfectly. “I’m not worried. We don’t complete until late 2025 and I think London will be booming again long before then.”

As well as selling property to the jet set, Caudwell spends much of his time pestering other billionaires to give away their money to charity. “That’s what I spend a lot of time doing, persuading rich people to be charitable.”

One person on his future hit list is Amazon founder Jeff Bezos. “If I was him, I would have pledged 99pc of my wealth immediately to charitable causes. It would still leave me with £2bn. Why wouldn’t you do that?”