NY explained on 27/03/2021 :
It was only fairly recently that we in the UK allowed a series of sequential
lights for indicators, which had been done on some American cars but had to
be changed to a simple on/off light if the car was imported into the UK. Now
that they are allowed again, I've seen some cars with them, and once you've
got over the novelty, they are very effective in showing which way a car is
indicating. https://youtu.be/1gXh1ghvKQg?t=878

Yes and certainly the most effective indicator lights I have ever seen.


At least we have unique colours for our indicators, as opposed to flashing
side lights or brake lights as some US cars have. I've seen some older cars
(probably 1950s or before) which had this, but it seems to have been outlawed
here around 1960 (am I correct with that approximate date?).

I would guess a decade at least later than that, but just a guess. An
easy conversion with an amber coloured lamp glass.