Mystery sack truck

This is a sack truck saved from a skip and currently residing in our garden.

Its last home was the Town Hall. The staff believed it to have come from Leamington station, and knowing my interest in railways asked if I wanted it. Of course I did. You don't get offered ex-railway stuff like this very often. Even if I couldn't keep it, at least I could find it a good home.

Anyway, knowing a local real railway expert, I asked him to come over and take a look. He examined the truck and pronounced that it isn't railway. More likely a Post Office truck, although it may have lived at the station for moving mailbags in the days when these were shipped by train.

Now I need to research GPO sack trucks to see if this should be painted or varnished. Since it will be living outdoors, at least in the summer months, the wood and metal all need proper protection. Ought I to paint the wood red ? Should it have lettering ? If so, what should it say ?

Is there a society for the preservation of sack trucks ?

Answers please.