I bought this in a charity shop about four years ago. I was going to use it as an address book, but it’s still empty. The paper is thin and fragile, and the clever metal mechanism is a bit rusty.
Made by Moore’s Modern Methods, 19-21 Farringdon Street, London EC4.
The company was established in 1909 and is still trading, as Moores Of London, except it isn’t in London anymore. That’s all I could find out online. I’ve emailed and tweeted them to see what they know about the early days. More to follow, hopefully.