Here is a bit of history on the use of hand signals by drivers: a 1954 Victoria newspaper report about a planned crackdown by the Victoria police against drivers who fail to use hand signals.

Note the comments in the right hand column:

“Blinking lights on both sides of car (i.e. turn signals) that have an indicator inside on the dash are allowable if the blink 32 times per minute. Certain mechanical hands on commercial vehicles are allowed [note: some trucks and commercial vehicles of the period had mechanical indicators or pointers that signaled turns or lane changes], but the lighted trafficators on some British cars [note: some British cars of the period had lights which illuminated, but did not flash, to signal turns or lane changes] are against the law.”