The range of banjos sold under the name of "Broadcaster" were stamped: "Made by J. & A. M. of London."
In actual fact they were made by the huge furniture, gramophone and radio company J.& A.Margolin Ltd. The banjos were inexpensive instruments, their wooden hoops being covered with nacrolaque, as were the fingerboards. The metal work (bezel, shoes, brackets, tailpiece, etc.) was of very thin lacquered brass.
Do you have a banjo by this maker? can you supply us some images?