I thought the amber turn signal lights came from Japan and I assumed it was just because they didn't figure out how US manufacturers did the combo thing.
I think you'll find that most parts of the world outside the Americas now require separate amber turn signals front and rear. They're the norm right across Europe as well as the U.K. now.
That or its a North American thing for the 'Rover
It could be, although the aftermarket thing sounds a distinct possibility. Manufacturers often have to adjust external lighting to suit local laws. All new cars here from 1980 onward were required to have a rear fog light, for example.
The only Australian made car that had red stop/turn/tail lights was for memory the 1956 FE Holden, the light lenses were red and clear in the tail light assembly. When it became mandatory for the turn signals to be amber in colour, people either found the next models indicator lens (the FC model-produced in 1958) would fit where the reversing (clear) lens was in the lamp assembly or aftermarket indicator lights (usually round) were fitted under the original light
Are you saying that Australian law required all
existing signals to be changed to amber, as well as requiring them on new cars?
We had a mixture of arrangements when turn signals started to become standard equipment on British cars in the 1950s. Some models went straight for separate amber signals, while others adopted the approach which was standard in the U.S. of using the existing brake lights as rear signals and putting a twin-filament bulb on the front to serve as a combination white parking/turn light.
Some models used a combination of the two methods. A lot of the Hillmans from the early 1960s had separate amber signals on the rear but combination white signals on the front. When the regulations demanded amber all round from 1965 they could no longer use combined lights on the front, because the rules still required front parking lights to be white (they became amber in the U.S. of course).
Going even further off topic, but the other signals which were employed here on some cars in the 1950s were little semaphore arms, pivoted and recessed into the B-pillars. Switching on the signal caused a solenoid to extend the arm on the appropriate side and light a small amber lamp on the end of it which could be seen both forward and rearward.
Back to LEDs though, and one other application which I don't think has been mentioned yet is modeling. There's the obvious application of red/amber/green LEDs for model railroad signals, but the yellow types and some of the new white types are also quite useful for things like interior car and building illumination.
