With thanks to RC and his lighting archive, this picture dates from the late 1960s and shows a Stanton display of "hardware" at an unknown exhibition.
Several things are of note, being an engineer, the first thing that springs to my mind is that the mounting base must be made of concrete to act as a counterbalance for those brackets! Although I guess it would help by the largest being opposite each other.
The display is unusual in having brackets and column bases, and it just goes to show how large the brackets were on the 10m and 12m concrete columns.
The loading must be immense on the joint even when they are in the best of condition, let alone after the weather has got in. Indeed sotonsteve and I saw one such failed bracket over the weekend - the column had shattered at the joint with rusty re-bar showing and lantern remains at the base.