Ah, ok; I thought that was the reason that there aren't many designs with a similar fold. Though thinking about it I should have realised this; I recall reading somewhere that the reason Brompton have kept production in the UK, with all the wage costs that entails, is because the manufacturing know-how is the major thing that stops them being pirated all over.
Actually not. There's nothing fundamentally difficult to rip-off about a Brompton.
Will Butler-Adams said in an interview that most of their sales are for the Chinese market and that, if they moved manufacturing to China (the obvious move when you think about it) the Chinese wouldn't buy it.
It's precisely because they are made in London than they are in such demand over there. People buy it in droves because they aren't only buying a bike, they are buying a bit of London Double-deckers, Black Cabs and Bobbies on the beat.
Gucci bags are no harder to make than other hand-bags...and so on.