Another example of the Crabtree voltage operated circuit breaker.
Almost identical to the red button version, this has a yellow test button.
The terminal covers are missing, as this was removed from an old installation.
Both sets of terminals have two screws each, in contrast to the Chilton types which have a single screw.
The E and F terminals are located at the bottom, one above the other.
The side view here shows how deep these devices were - over 70mm just for the casing, with the main lever and test button protruding even further.
The yellow button has 'Press to Test' around it. The main lever has OFF marked in white and ON in red.
This video shows the internal mechanism in detail, and a test to see if the device still operates.