The class originated back in the 1860's for the transport of gunpowder for mining, construction and probably army ordnance. The original vehicles were known as 'PV' although Register records from 1886 only show the class as 'P'.
From the early 1900's to the 1950's, explosives were moved from Deer Park ( Nobles, later ICI ) to Laverton where the explosives were moved by 2 foot tramway to bunkers for storage and transfer to ships. This location was the Trugannina Reserve. Ships with explosives were not allowed within 1 mile of the port of Melbourne. Explosives were moved from the bunkers to the ships via lighter.
The original vans were gradually scrapped through to the 1950's. Some vans that had been rebuilt in the 1900's were scrapped prior to 1960 as unsuitable for auto coupler conversion.
During the early 1950's a fleet of 54 vans were built using old underframes, steel body frames and sheet plywood sides. The vans were painted bright red with black 'EXPLOSIVES' lettering on a yellow background. This made the vans quite distinctive amongst the usual 'sea' of 'wagon red' vehicles.