Churchward's standardisation aims meant that a number of tank locomotives were produced that were based on these tender locomotives. The 2221 class of 1905 were a 4-4-2 tank version of the County class, indeed they were known as the "County Tanks". These were then developed into a 2-6-2T design, being produced as the 3100 class in 1903 and the 3150 class three years later. Smaller 2-6-2Ts, the 4400 class were introduced in 1904 and were succeeded by the slightly larger 4500 class in 1906. Two very different freight tank locomotive types appeared in 1910. The 4200 class was a tank version of the 2800 class, but a demand for small locomotives for working on dock and branch lines was met by the 1361 class, a new design based on the old Cornwall Minerals Railway 0-6-0ST design but using as many of Churchward's standard parts as possible.