How do two signal boxes at the same location work together?

[beast66606]

16 minutes ago, The Stationmaster said:

Were the Distants slotted there or not?  

 

There were places on the GWR where the Distants were not slotted - Reading Main Line East and Reading Main Line West being a prime example where the distance between the two 'boxes was only 770 yards and Regulation 4A working applied using the ex GWR bell signal 'Line Clear to Clearing Point Only'.    Interestingly that also applied at Shrewsbury - and still applied when I visited the Shrewsbury 'boxes in the early 1990s although the Regulation itself had long been discontinued as a Regulation but was included in the Signal Box Special Instructions instead.

 

Slotted and electrically released depending how far out they were (iirc)  - it must have been fascinating watching the boards dropping off for a Birkenhead Fast, stop signals from South to North and then the distants working backwards under the stops (and vice versa for a Paddy of course)

[Compound2632]

4 hours ago, caradoc said:

 

IIRC The practice was to have the signalling instruments in a central location, eg the station  buildings, and the 'boxes' at both ends worked the points and signals.

 

 

Although common, irrespective of the number of signalboxes, the practice of having the signalling equipment split between the station office and the signal box was a contributory factor in the Abermule accident of 26 Jan 1921 - having all the equipment co-located in the signalbox was a key recommendation of Col. Pringle's report.

[Compound2632]

4 minutes ago, beast66606 said:

 

Slotted and electrically released depending how far out they were (iirc)  - it must have been fascinating watching the boards dropping off for a Birkenhead Fast, stop signals from South to North and then the distants working backwards under the stops (and vice versa for a Paddy of course)

 

That's the description I was half-remembering. 

[The Stationmaster]

8 minutes ago, Compound2632 said:

 

Although common, irrespective of the number of signalboxes, the practice of having the signalling equipment split between the station office and the signal box was a contributory factor in the Abermule accident of 26 Jan 1921 - having all the equipment co-located in the signalbox was a key recommendation of Col. Pringle's report.

And took many years to sort out - with it never being sorted in some places before they either closed or were resignalled (or designalled).

[caradoc]

1 hour ago, The Stationmaster said:

And took many years to sort out - with it never being sorted in some places before they either closed or were resignalled (or designalled).

 

IIRC (again) Nairn was the last such location, lasting until comparatively recent times.