Black and Yellow Shunting Signals

[Belperpete]

The SR use of electromechanical disc signals as subsidiaries to colour light main aspects does in retrospect seem a bit incongruous. I think there were places where the colour light had both a miniature yellow subsidiary and a disc. And there were places where they used the electromechanical discs as banner signals, with a black band on the white enamel disc, such as Victoria.

There are LED signals on the underground configured to give a display mimicking a traditional disc signal, using red and white LEDs. I wonder if there is a yellow version? Having said that, I can't recall ever seeing a yellow disc on the underground?

 

[zwk500]

The Southern Railway/Southern Region only used floodlit disc shunting signals in colour light signalling areas. This was in response to a recommendation of a sub-committee of the Railway Clearing House in 1934 that shunting signals in colour light areas should be of the 'position' type (as opposed to displaying miniature 'colour' aspects). The exact type of signal was not specified. Alternative solutions adopted by the other companies included the use of banner type shunting signals or position light signals. The Southern Region began installing position light signals in the early 1960s.

Is this recommendation why London Underground uses Discs not shunting aspects?