A large proportion of BR Western Region was resignalled in the 1960s and 70s. Apart from a few isolated schemed where colour-lights already existed (Paddington-Hayes, Bristol, Cardiff), the majority of the signalling being replaced was mechanical, with semaphore signals and points worked from lever frames.

The resignallings came at the same time as a number of other economies in the railway organisation:
* Dieselisation, replacing of steam locomotives
* Rationalisation of the network, including the closure of many stations and lines.
* MAS, a huge saving in equipment, maintenance and manpower by centralising control of MAS equipment into the new panels.

MAS control panels allow the setting of routes electrically, instead of mechanically. They are a lot less labour intensive than a layout signalling with mechanical equipment. Critically, a much larger area can be controlled by each person.

The then new panels utilise square tiles called ‘Dominos’, patented by a Swiss company called Integra, to construct the panel diagram. Each Domino is 40mm square and has a small section of the layout on it, such as one signal, or one set of points. Many hundreds of small Dominos are then formed into a mosaic to build up the required panel diagram. Domino panels are supplied in the UK by Henry Williams in Darlington.

The WR Domino panels are special in that they use rotary switches for the ‘entrance’ controls, instead of the push buttons that most other regions use.

Domino panels were installed on the Western Region at the locations below. Large installations are shown in capitals.

Dates drawn from the BPSR.