Could be the Victorian electroplaters. See below from earlier posts:
Re: Some great men and women of Birmingham..
There is an exhibition running at Tate Britain until May 25th 2015 called "Sculpture Victorious". The sub-title is "Material Wonders of the Victorian Age". Reference is made to the Birmingham firm of Elkington & Co. Post 8 of this thread, by Dennis Williams, gives information on the founder of this firm George Richards Elkington. This from the Tate, "The Birmingham firm of Elkington & Co transformed sculpture through its patented forms of electroplating and electroforming in the 1840s, in which an object, or a mould, could be dipped in a metals solution which was gradually decomposed using an electric current, leaving a thin shell of gold, silver or copper on the surface. Electrodeposition was cheaper than traditional casting, and this combination of innovation and thrift won Elkingtons prestigious commissions".
An illustration of Elkington's sculpture making process is provided on the attached link. Dave.
https://myweb.tiscali.co.uk/speel/otherart/elkingtn.htm