The label on the instrument's lid reads "WILLIAMS & CO., ELECTRIC AVENUE, BRIXTON S.W.". This is presumably the dealer that sold it, as the manufacturer's name and serial number are stamped inside. Pitch/tuning is A455.
The instrument is a simple folding harmonium with one rank of reeds and no stops. The lid is hinged and was originally operated by a spring ratchet system that allowed it to be raised and lowered by means of a metal knob to the left of the keyboard. However, this system is no longer operational.