When Nicholas Bowman-Scargill’s mother made a joke at a Sunday lunch about restarting the family’s 170-year-old Fears watch business, he laughed. The company closed 60 years ago, and its revival wasn’t something he had thought much about.

But two years and 40,000 pounds ($49,600) of his own money later, his own Fears watch is to have its debut this week at the SalonQP fair in London.

“It was my eureka moment,” Mr. Bowman-Scargill, 29, said. “I’d been working at Rolex for two and a half years, and although I was enjoying working in the workshop, I have always wanted to try my own thing and create my own company.” He was sitting in the office at his home, a 1920s townhouse on a gated cul-de-sac in the London Docklands, in early September, just days before the first 200 watches were delivered.