I follow him down the wooden stairs as he heads off to find his old childhood bedroom in the basement. It’s a neat guest room now, but young Bill spent hours, even days, in here “thinking”, as his sisters put it.

At one point, his mum was so fed up with the mess that she confiscated any item of clothing she found on the floor and charged her stubborn son 25 cents to buy it back. “I started wearing fewer clothes,” he says.

By this time, he was hooked on coding and, with some tech-savvy school friends, had been given access to a local firm’s one computer in return for reporting any problems. Obsessed with learning to program in those nascent days of the tech revolution, he would sneak out at night through his bedroom window without his parents knowing to get more computer time.

“Do you think you could do it now?” I ask.

He starts unwinding the catch and opens the window. “It’s not that hard,” he says with a smile as he climbs up and out. “It’s not hard at all.”