Ivory bakelite with solid brass pins. Pictures and text provided by Loz Pavier.
Underneath, remains of a 'guarantee void if seal broken' sticker is applied. This is more likely to be from a previous safety of PAT test, than a manufacturing sticker.
Note also that typical screws are not used. Small nuts with a complimenting washer are used to clamp cable down to the relevant pin. Slots are provided for a screwdriver, however they are unreliable due to the length of the thread from the pin.