"No one even thinks of watchmaking as a possible profession these days," he said.
In 1905 Hans Wilsdorf, a 24-year-old Bavarian who learned watchmaking in Switzerland, set up a business in Hatton Garden to distribute watches.
Once the home of light industries such as brewing and watchmaking, many of the old commercial buildings have recently been converted into apartments.
Sapphire is a relatively common material in high-end watchmaking.