This kit is designed to model GWR diagram Y4 ventilated and heated banana vans. This diagram was a further conversion of box vans built to diagram V16 with twin ventilator binnet ends which had been fitted with insulation (sealing the ventilators) for use as meat vans during WW1. The insulation was retained along with the external, though now sealed, ventilator bonnets and steam heating fitted to help ripen the bananas between port and market. It is unclear how many vans were converted as many of the 300 were converted to meat vans had reverted back to standard ventilated vans before the banana van conversions started. Best estimates of the Y4 banana van fleet are around 100.
Natually changes were made as years passed, though the majority of the vans seem to have remained visually unmodified until withdraw in the 1960s. The most obvious chnage was the elimination of the bonnet vents if the ends required replanking, however a small batch of purpose-built 'Y4' vans were built after WW1. This batch had RCH Morton brake levers in place of the spring-applied Dean Churchward brake levers supplied with this kit and were built without the bonnet vents. Eventually these vans were sorted out and given their own diagram Y12 and could be modelled from this kit, but removing the moulded on vents is probably a job for more experienced modellers.
As the central sliding ventilator cover is supplied as a separate part this kit does offer the opportunity to model the GWRs 16' ventilated box vans with angle-braced ends, covering diagrams V14 and V16, in additon the ends for the V12 kit (on the same sprue as th side mouldings) feature the side vent slats and X brace ends, so the V12 vans and some of their many derivatives can also be recreated.