This vacuum braked van is probably unique because it was built to carry gunpowder.  Most were converted from GWR 'Iron Mink' box vans, rather than speciically designed for the purpose.  The GWR telegraph code for gunpowder vans was 'Cone', with a TOPS code of CXU.

105777 was built in 1939 and was designed for safety.  It has a wooden 'non-spark' lining, and hooks for the hanging of nail-less leather over-boots for the operatives to cover over their hob nailed boots, inside the doors.  Brass or copper screws, hinges and kick plates were used to avoid danger of sparks.  Loads were securely roped to special cast pockets on the inside walls in order to avoid the danger of an explosion.  Other modifications include a tie-bar and heavy duty type axle boxes.

This particular example was last used on traffic to the Gypsum mines in Mountfield in East Sussex.  It was delivered to Quainton on 24 July 1981.