They were the last new GWR 4-4-0 design and by far the most modern, with inside frames and outside cylinders. They were designed as a part of Churchward's standardisation plan, but were found to have a front end too powerful for the wheel arrangement and all were withdrawn by the early 1930s. They were designed, in part, for the Hereford to Shrewsbury LNWR line over which the GWR had running powers, but on which they were expressly forbidden to use 4-6-0 locomotives. The 4-4-0 Counties were in effect a shortened GWR 2900 Class, providing engines powerful enough for the trains but with the requisite four-coupled wheels.