NY submitted this idea :
My mum's 1960 Morris Minor had orange (not red/white) indicators, at least
when mum bought it second-hand in 1966. They may have been fitted after-sale,
because it also had trafficators that still worked. I wonder if Mum had them
fitted when she bought the car.

I don't remember any white indicators, except in US cars. I half
remember a conversion of the mechanical arm trafficators, where the
trafficator slot had a fixed orange sticky out lens mounted over the
slot, with a built-in flasher.