Allow me to speculate on something I’ve observed. Let me preface by saying that I have seen no evidence that this is more than an oversight but as the subject is my field of study I noticed it and the ramifications could be quite interesting. This is not to nitpick but to create a narrative reason for an anachronism.
The date is 1893.
It is repeatedly mentioned that photographs encountered in the Neath are daguerreotypes, a process introduced in 1839 and perfected by the 1850’s. By the 1890’s it was barely used, having been virtually entirely replaced decades before by ferrotype, ambrotype, wet-plate and, by 1893 dry-plate glass. By 1889, Eastman Kodak was producing rolls of celuloid film and amateur photography had exploded with the introduction of the original Kodak the year before. Assuming that post-lapsarian London suffered from technological stagnation and is 30 years behind the surface they’d be ca. 1860’s: Solidly in the wet-plate photographic era.
So, why the prevalence of daguerreotypes?
If you’ve ever seen a daguerreotype there’s a particular quality that makes them different from any other medium: they’re perfectly reflective. The substrate is made of copper plated with highly polished silver. In fact, image quality is directly tied to how well the plate is polished. The photograph is a fine silver/mercury amalgam sitting on the surface of a mirror. This is why the daguerreotype was referred to as a "mirror with a memory" contemporaneously.
Given certain groups interests in mirrors, does photography actually hold more power in the Neath than we’re aware of? What exactly does concentrating the image of an individual onto the surface of a mirror do?
I leave you with that.
Yr. Obd. Srvt.
Dr. E.J. Hamacher