I thought of Josephus Smith also, but two of my books show his silverplate mark as J.S in a single cartouche. Don't know anything else about the firm.

John Sanderson & Son Ltd. did make knives that had pearl like handles.
He produced a lot of flatware from roughly 1918 to 1979. He doesn't show up in my books, but they generally have older marks in them. John Sanderson is just a possibility, I'm not sure it's his mark.
Pat.