All the parts are low quality. It's a £200 bike (or would be if it was assembled in the Far East, like everything else) sold for £1000. You're paying for London labour costs, a lot of marketing and a fairly decent profit margin. The latter is helped by aggressive IP enforcement (the patent is long expired, but the general appearance is trademarked) and highly dubious retail price maintenance; Brompton stop supplying dealers that sell at any meaningful discount, and always have.
It still folds smaller than anything else and holds up reasonably well. Except the wheels, which can be dreadful and usually need taking apart and rebuilding when new.
