The first British horror movie to be rated 'H' for horrific, which was brought in by the British Board of Film Censors in 1933 for films that were deemed too horrific for children under 16 to see after the early '30s Universal horrors shocked audiences.
The Stainsbury machine is a Braille shorthand machine. Henry Stainsby--superintendent of Birmingham Institution of the Blind in England--and Alfred Wayne developed several of these devices, commencing in 1899. The one seen in the film is similar to the "Improved Stainsby Braille Writer" of 1933.
Filmed early April 1939, released November in Britain, March 1940 in the US. Bela Lugosi shot this feature after The Gorilla (1939) and before The Phantom Creeps (1939).
Holt's statement, "As the walrus said to the carpenter, the time has come . . . " is a reference to the poem, "The Walrus and the Carpenter", from Lewis Carroll's '"Through the Looking-Glass and What Alice Found There".
This 1939 British production was acquired as a negative pickup by "Poverty Row" studio Monogram Pictures, which changed the title to the more graphic "The Human Monster" in 1940 for US release.