A home blade directly infront of a distant blade on the same post.
The home spectacle plate with a red lens and clear lens.
The distant spectacle plate with a yellow lens and green lens.
But, I would imagine that when both blades are horizontal, at stop, the combined yellow lens and red lens would not provide a distinct red light.
Yes, they where so called Coupled Home and distant signals
but the Signal shows Red when both blades where Horizontal.
The mechanismus of the Signal granted this.
The Home arm, in front, had one red Lens and one clear , while the distant arm, in back, had one green lens and one clear . A swinging yellow Lens, pivoted in the Home arm and with a pin in the distant arm running in a slot, was located between the arms, which were both pivoted at top of the arms . When both arms were horizontal, the light from the lamp passed through the empty lens in the distant arm and the red lens in the Home arm.