Originally built as an SPA plate wagon, the wagon depicted by this model was given over to departmental use soon after its construction and was one of some 300+ SPAs re-coded to ZAA in 1983 – with many receiving the BR Engineers Grey and Yellow colour scheme. Like most wagons in the departmental fleet the ZAAs were given fishkind names – for SPAs these being ‘Pike’, ‘Seahare’ or ‘Sea Urchin’. ‘Pike’ wagons were unchanged from their original design, however they proved less than ideal for departmental use and so many were modified leading to further changes of TOPS codes and names.