At the turn of the century the GWR needed powerful express locomotives for the Shrewsbury and Hereford line, where no six-coupled locomotives were allowed. So Churchward designed the County class as a 4-4-0 derivative of the 4-6-0 Saint class. They were the last new 4-4-0 locomotives of the GWR and the first ten built in 1904 got the numbers 3473 to 3482.

Like the Saint, they had outside cylinders whose size was not changed. Since these big cylinders needed heavy counterweights which now had to be divided between only four wheels, this led to a heavy hammer blow induced in the tracks. Another effect of the big cylinders was that the tractive force was a bit too high for two coupled axles. 

Until 1912, a total of 40 had been built, of which the last ten got a superheated boiler from the start. After the second batch had already got numbers starting with 3801, in 1912 they were renumbered 3800 to 3839. A development of the County class was the class 2221 “County Tank” that got the same cylinder dimensions, but a smaller boiler.

Possibly due to their rough riding, they were withdrawn between 1930 and 1933. All were scrapped, but the Churchward County Trust announced that they would build No. 3840 “County of Montgomery” new from scratch. In May 2024 they machined the front part of the frames.