zGWR Castle Class 'Caerphilly'HOR R30328 Hornby GWR, Castle Class, 4 6 0, 4073 'Caerphilly Castle' Era 3 2023 Catalogue The Castle Class was designed by Charles Collett, the successor to legendary GWR engineer George Jackson Churchward. In truth, Castle Class is nothing more than a nickname owing to most examples of the class being named after western castles with the official GWR designation being the 4073 class. This name comes from the first example of the Class 4073 Caerphilly