Twenty steel vans were built in 1958. Numbers were BP 3 to 22. They were fitted with passenger speed bogies, type "BX" meaning "Box Express".
When designed, the class letters were going to be 'XP'
_BP_ 1 and 2 were originally _TT_ bogie boxvans had been recoded and renumbered.
Further construction was split between BP vans and _BB_ vans fitted with plain bearing bogies. Whilst the steel BP number group was 3 - 102, continual conversions in and out of the class saw only thirty to forty vans in service at any one time.
BP 98 was fitted with a head end power unit in 1961 for head end power testing prior to standard gauge operation. When the power unit was removed, the end panel was replaced with flat sheet steel.
In the 1979 recoding the class was recoded to VBPY.