Image: Various mid-twentieth century auto-mobiles pass through an intersection in an urban area. A large plinth stands in the centre of the intersection and is marked with the words ‘Keep Left’ and left-facing arrows
Black Diamond Corner, 1950. The third and final ‘silent cop’ is visible in the centre of the intersection
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Image courtesy of the State Library of South Australia, SLSA: B 24297, http://collections.slsa.sa.gov.au/resource/B+24297, Public Domain