One looks like an ex BR Ferrywagon (as mentioned above) - "VJX" on Tops. Once BR had stopped sending it's own ago overseas , they had very little commercial use in the UK , and we often used as barrier wagons etc for dangerous goods flows. Usurped by much more modern Cargowaggons etc for European traffic , ditto the VXX fleet domestically.
It was a relief for BR to sell some off for internal use to the MOD , which looks line one in the picture.