Four Class 37 locomotives in the departmental Class 97/3 number sequence were allocated to Network Rail around 2007 for various duties including the development of ERTMS cab signalling on the Cambrian line and autumn rail head treatment trains. The locomotives were prepared for their new duties at Barrow Hill in 2007 and 2008 after being withdrawn from regular service and, in some instances, a protracted period in store. Numbered 97 301-304, three of them have centre head code panels whilst one has rebuilt bonnet fronts which are flush with marker lights. All four locomotives are finished in Network Rail yellow livery with a mid grey roof and bonnet tops. Bonnet side grilles and shoulder grilles are painted black, as are the underframes. The large radiator grille is finished in the main body colour. It is worth mentioning that the main body colour adopted for Network Rail locomotives and rolling stock is different to warning panel yellow, a feature correctly replicated on the model.
The model was released at the same time as a Class 37/0 in EWS livery offering the chance to include such locomotives on layouts based on an up to date theme. The Network Rail Class 97/3 could turn up almost anywhere given the wide range of departmental duties for which they are employed. The model proved to be very popular, as most models finished in NR yellow seem to be these days!