BPRSCo Power Frame
Amongst the early types of frame introduced during the 1900's for early power schemes was this type of draw-slide frame.
The levers have coloured handles equivalent to the colours of conventional levers - red for signals and black for points can be seen here. Slides without handles are out of use. All points and signals were worked by pneumatic power.
When signals returned to danger automatically behind trains, the slide moved back into the frame - this could give a stranger a nasty shock!
This type of frame was used extensively on the Great Central Railway, and to a lesser extent with other companies such as the London & South Western. Some examples survive to this day.
The example illustrated is at Immingham Reception Sidings.