As opposed to Unlimited? A pic taken by the Evening Post in Grant Road, Wellington. In NZ the sign meant the open road limit applied, unless conditions made that unwise when the general urban limit applied. At the time the open road limit was 50 mph (80 km/h). In 1962 it was increased to 55 mph (88 km/h) and again in 1969 to 60 mph (96 km/h). Speed limits were converted to km/h in 1975 in line with general metrification at that time.
It's not obvious why this location was chosen for the pic; it would not have been a suitable street for higher than the then general urban limit of 30 mph (48 km/h).