I took the bridge and tailpiece apart today to give them a little clean. When the string holder part was separated from the baseplate I found, possibly, initials etched into it. It might be M. G. Quality Control? More mysteries never to be solved.
The string saddle and its baseplate appear to be cut from sheets/slabs of brass which are chromed before the parts are cut out as, on the baseplate, the edges are brass and the faces chrome, and the saddle the opposite way around with chrome edges and brass faces.The brass surfaces are too clean to just be worn away chrome. Presumably they use large pre-chromed slabs of brass and cut/stamp out the pieces before machining.
They've cleaned up nicely, even the brass screws.