Railway Signs and Signals of Great Britain

Very occasionally, co-acting colour light signals are provided. There were examples of these in the first scheme to use mainline colour light signals, at Marylebone (LNER) in 1923. Usually the duplicate signal will be ground mounted (as at Marylebone) [7.19], and it may even be positioned on the opposite side of the track [7.20]. Exceptionally, a colour light signal head was provided in association with a semaphore signal [7.21].

[7.19] Co-acting Signals.	[7.20] Co-acting Signals.	[7.21] Co-acting Signals.

For a few years, banner repeaters with yellow arms were provided in some places (without a distinguishing letter "R") [7.23 - 7.26]. The Southern Railway continued to use red banner repeaters, endorsed "R" (see [7.11 - 7.14]).

[7.23] Banner Repeater with Yellow Arm ('on').	[7.24] Banner Repeater with Yellow Arm ('off').


[7.25] Fishtailed Banner Repeater with Yellow Arm ('on').	[7.26] Fishtailed Banner Repeater with Yellow Arm ('off').

The impending introduction of four-aspect colour light signalling had left signal engineers pondering the best form of repeater signal to use where sighting of a signal was restricted. The banner repeater, being a 'position' type signal, was suitable for a semaphore signal but was not considered appropriate for use with a colour light signal. Logically, a repeater of colour light signal should itself be of the colour light type. If however the signal, and hence its repeater, were to be displaying a red aspect, drivers would have to pass the red light in the repeater to draw up to the main signal, which would be undesirable. To overcome this, the Southern Railway had proposed using what was termed an 'auxiliary signal' [7.27 - 7.30] in preference to a repeater. An auxiliary signal comprised a small three-aspect head and a permanently-illuminated white St. George's cross on a black background. The auxiliary signal repeated the aspect that would be shown by the previous signal, thus a single yellow light [7.27] was displayed when the signal ahead displayed red, or double yellow [7.28] when the signal displayed single yellow. The auxiliary signal would display a green light [7.29] when the main signal displayed either a double yellow or a green aspect. To prevent 'reading through' from the signal in rear, the auxiliary signal would display the white cross alone [7.30] while a train was standing at the main signal. Under normal circumstances, a train would never approach an auxiliary signal in this state. In the event, no auxiliary signals were needed in the earliest schemes and it subsequently became normal practice to provide banner repeaters for colour light signals with restricted sighting.

[7.27] Auxiliary Signal showing 'Caution'.	[7.28] Auxiliary Signal showing 'Warning'.


[7.29] Auxiliary Signal showing 'Clear'.	[7.30] Auxiliary Signal (normal aspect).

In 1926, fog repeaters were provided at two signals at Forest Hill (Southern Railway). These could display either a red or green aspect and were identified by a plate bearing the letter "F" [7.31 & 7.32].

[7.31] Fog Repeater ('on').	[7.32] Fog Repeater ('off').

Electric light repeater signals were occasionally provided, particularly for use inside tunnels where it was not practical to install a banner repeater signal. A yellow aspect [7.33] was displayed when the signal ahead was 'on', or a green aspect [7.34] when the signal ahead was 'off'.

[7.33] Electric Light Repeater Signal ('on').	[7.34] Electric Light Repeater Signal ('off').

In 1927, a banner repeater signal was provided to repeat the Down Main distant signal at Haywards Heath North (Southern Railway). The banner had a yellow fishtailed arm on a black background and was surmounted by the letter "R" [7.35 & 7.36].

[7.35] Fishtailed Banner Repeater ('on').	[7.36] Fishtailed Banner Repeater ('off').

Section 7: Co-acting Signals and Repeater Signals

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