Foster & Stonn
Foster & Stonn (also known as Foster's) was a 19th century photography firm based in Bloomsbury and owned by Tom Foster and Stonn. It was mistakenly known by some customers as Foster & Son.
Aware of Tom's dreams of being an artist, Stonn decided that they could capitalise on the spiritualist craze by forging spirit photographs, something which became easier when Stonn came into possession of a Malampus crystal. The business thrived thanks to the spirit photographs as well as taking photographs of the dead.
Storage of the negatives of both types of photographs caused the dead to enter the bodies of the living as Revenants. This was discovered by Madame Vastra, who convinced Stonn to destroy the Malampus lens whilst the Revenants attacked the shop. The firm was then closed down. (AUDIO: A Photograph to Remember)