Similar to the metal cased Bill Crown unit, this one has a moulded brown bakelite case.
Two screws secure the cover, which has the maximum ratings 60A and 250V, plus the Bill and Crown logos.
There is no back to the device - a separate white plastic backplate was available which fixed to the wall behind the ceramic inner section.
The earth bar can be seen to the left, with two screws at each end.
This example has two 30A fuses and two 15A fuses.
Note that some of the brown spots on the fuses are cracked and deteriorating. If these fall out, live screws are exposed.
The terminal for circuit neutrals is at the top right. Incoming supply connects to the two terminals below the switch.
The switch has a mechanical interlock, preventing it from being switched on when the cover is removed. A metal tab which fits over the switch prevents the cover being removed when the switch is on.
The lower section has two 15A fuses, with the incoming L and N terminals on the right side below the switch.
The white cloth in the fuse positions is probably asbestos.
The 30A types have a cloth flash pad and copper blades. The 15A has no flash pad and brass blades.
The inside is marked For AC Only, Part No AC 6002, Made In Gt. Britain.