Dating the Post Box

This post box has been in the collection for some time, and we are trying to date it. So this picture has been posted for Laurie.

There is a suggestion it may have come from the Briagolong Railway Station, which would have closed in the mid 1950s, I think. And passenger services closed well before that time - the 1950s were goods trains only, with timber from the mill????

There are some mail closure times on the door, but they don't really help.

Any ideas, Laurie?????