The County class of the GWR was developed by Hawksworth during World War II and was intended for mixed service. It was the last of a series of ten-wheelers begun by Churchward in 1902 with the Saint class. It included some innovations such as 280 psi boiler pressure and dual chimneys. However, the pressure was later reduced to 250 psi to save on maintenance costs, and later examples had single chimneys. Special optical features for GWR locomotives were the continuous splashers over all coupled axles and straight nameplates.

After two batches and 30 locomotives, production was discontinued as the staff evidently preferred the locomotives from Hawksworth's predecessor, Collett, and there was no need for more. The County class was retired between 1962 and 1964. Although not a single locomotive has survived, number 1014 “County of Glamorgan” is currently being built new.