White three pin fused connector.
It still has the remains of an ancient 2 core single insulated flex attached.
The plug is removed by undoing the round nut in the centre. The two small screws only secure the flex in the plug.
The brass threaded post in the centre has a small nut which secures the base cover, and the same post also accepts the nut which secures the plug into the socket.
The base has a section removed, which is where the circuit wiring would have entered.
The earth contact extends to the centre brass post, which although ensures it cannot become live, also means this 3 pin connector can only be used as L-N-E, and certainly not on a master-slave type system where one pin would be used as a timing signal.
Made in England.