I expect they got a contract with one of the Taiwan Manufacturers to make them for the assembly in London
an upside down pull from the bottom dual pivot. the mid 90s they got CLB in France to make them a single pivot then..
warrantee is thru Brompton via your dealer.. get the tech info from them. I wouldn't worry about the Who made them ..
I took out the Fibrax Brake blocks and put salmon Kool Stop Dura 2 inserts in ..
removed set screw on the holder, lets the insert slip out towards the back .