S.G. Bailey & Co had a manganese mill at Great Western Docks, Plymouth, the machinery & plant were offered for sale Western Daily Mercury 15.9.1888.
There were several press reports in January 1888 of the bankruptcy proceedings of Joseph Bailey of Campelhay, Tavistock. He had a son Stanley Bailey - was that S.G. Bailey? The accounts mention various members of the family owning mines (not all manganese) including Langstone, New Phoenix, Wilhelmina, Weare Quarry (Saltash), and manganese mills at Millbay Docks (presumably the above).