This is the  Wrenn W5001 "ROSS FOODS" Fish Van, running number E87231 from the Wrenn, Basildon Period 2 (Triang/Wrenn)  era. The van was issued by Wrenn, Basildon factory over 2 periods of production (2/3), the third/fourth examples coming from Period 3 issues..

They come complete with either Period 2 (Triang/Wrenn) or Period 3  boxes with yellow plastic inserts type WA2. 

As with all late Period 2 and P3 wagons they have  metal rimmed wheels, as opposed to early Period 2 with plastic wheels/axles.

Condition of the Vans/boxes condition is "near mint", for their age.