Plastic surface mounted MK switch with neon indicator.
This could be used as a local isolator for a fixed appliance such as an immersion heater, which would normally have it's own separately fused circuit.
Unlike many other items of this age, the back is completely enclosed, so would comply with current requirements.
Cables enter at the top at bottom of the device, and would be surface fixed. There are two mounting holes, one at each cable entry.
Alternatively, the darker plastic section in the centre could be removed to allow cables to enter from inside a wall or behind a wooden board.
The incoming and outgoing terminal screws are located on the sides of the switch. A single earth terminal is provided at the bottom centre, with an earthed plate extending around the switch mechanism.
The two brass screws on the front can be removed, the centre switch mechanism can then be separated from the backplate to allow wiring to be connected.