@EarnestEccentric Pretty sure we called it a dipswitch in my part of 60s Britain. not to be confused with w dipstick which, in later times, when applied to a person, suggested a lack of foresight . We referred to dipping our lights rather than dimming. This reflected the the use of a second filament in the bulb which had the effect of producing a beam with a flatter top which pointed downwards and slightly towards the left by a few degrees.
I'm talking about the cars that I had experience of, so there may be other ways used to avoid dazzling oncoming traffic which didn't know about.