Family cars started to trickle back onto British roads after the end of the Second World War. These were cars that had been stored away in garages during the war because petrol had only been available for essential work.
Consequently many of the cars that I saw as a child in the 1940s were old ones from the 1920s and 1930s. Some were even earlier. What struck me particularly about these old cars were their indicators for turning left or right.
The old cars indicated that they were turning left or right with a control that swung out a little lever-like arm - see the photos. These were widely known as 'flippers' but their formal name was 'trafficators'.
The trafficator system was not at all satisfactory because the mechanism tended to jam so that the flipper was either stuck in or out all the time - and there was no flashing light to focus anyone's attention on it.
Trafficators sat in a recess, which could become gummed up with dirt, grime, polish and all manner of things, and they could be frozen stuck in winter. Water could seep into the aperture and (maybe because of this) the solenoids that worked the arms failed or jammed. Bulb life was not brilliant either, possibly because the trafficator arms opened and closed with a bit of a 'thwack'. Trafficators were also a pedestrian liability. They would suddenly pop out at head, throat or arm level and I understand that several people were injured by them.
My father said that if you turned the engine off before the trafficator had come in, it would stay sticking out and he had broken several by getting out and walking into them.
Some buses and lorries were fitted with trafficators. They were usually somewhat larger than those on cars and vans. Some buses also had complimenting left and right pointing illuminated arrows on the rear, and these were often retained after the advent of flashing indicators.
As far as I know there was no car indicator to show that a car was slowing down.
The solution to this and to the unreliability of trafficators was hand signals. The driver opened his window and stuck out his arm as explained in more detail on the traffic control page.
As you can imagine hand signalling was not a rapid reaction process. To add to the problem, it relied on the driver behind concentrating on the car in front rather than on the road generally.
The fact that trafficator indicators did not result in more accidents must have been due to there being so little traffic on the roads.
My first car was a 1960 VW Beetle with trafficators, which, after use, I always had lean out of the window and slap down again by hand because they refused to retract into their slots. This was easier on the driver's side of course. So if I didn't have a travelling companion to do the slapping-down on the nearside, every time I turned left I had to resort to hand signals, knowledge of which was mandatory for the driving test in those days.
If I recollect correctly trafficators were made obsolete on new vehicles by law at some point in the 1960s. I remember, as a child, my father commenting that it was "...a ****** good thing too".