[broadgage]

Re the first picture in post #191, I have several NOS torches that are very similar in size and shape but that are equipped with red and green filters that may be slid upwards in front of the reflector.
The packaging suggests that cyclists could carry one as a spare since the red filter would allow it to replace a failed front or rear light, rather than carrying two spares.

The red lens at the back emits only a very feeble light, I suspect that it was simply to confirm that the light was lit if used as a cycle headlight.

I have seen these with an orange case as shown or in blue.