Analogous to the “Large Prairies”, Churchward had a smaller engine built in 1905, which was given the number 115 and founded the “Small Prairies” family. With a driving wheel diameter of four feet and 1.5 inches, smaller cylinders and a smaller boiler, it was designed for use with passenger and goods trains on branch lines. The ten other production engines were initially given the numbers 3101 to 3110 and became the class 4400 with the new designation scheme of 1912. Since they were only suitable for shorter distances with the small wheel diameter, further locomotives with a driving wheel diameter of four feet and 7.5 inches were built since 1906.

By 1912, initially 30 engines with the numbers 2161 to 2190 had been produced. In 1912 they were re-designated class 4500, under which they are better known. Another 25 engines were made by 1915 and finally the last 20 engines in 1924. Although they could be used more widely than the Class 4400 thanks due to their larger wheels, they were primarily used on the hilly branch lines of the GWR in South Wales and Devon. Three were loaned to the Rhondda and Swansea Bay Railway, which was taken over by the GWR in 1922. The last engines were retired in 1963 and three were preserved, with one operational in 2020, one being refurbished and the third on display at the Severn Valley Railway.