Here’s a little bit of history: an old street sign showing the pre-1967 UK-style Postal District Number: SE9.
I’m quite amazed the sign has survived so long, unless perhaps it is a deliberate, heritage-based decision to keep and maintain it.
The old codes don’t seem to be in the first edition Melway, but I did find them in an older Collins street directory that I have. As with London postcodes, the letter is a direction from the GPO (or C for Central).
I don’t have the time or inclination to type them all out, but there is a full list in Wikipedia: Melbourne Postal District Numbers.
Far distant places such as Dandenong, Frankston, Glen Waverley, Mitcham and Eltham appear not to have had Postal District Numbers.
Anybody spotted old signs like this elsewhere?
Update: Tony found (most of) a similar old sign in Flemington.
Update April 2014: It looks like the North Road sign has been removed. Shame.