In 1902, WAGR ordered twelve Ten-Wheelers from Baldwin for the Murchison line with a low permissible axle load. They were a scaled down version of the Ec class Pacifics that had also been delivered by Baldwin a year earlier. They got the nickname “Baby Yanks” because the Ec were also called “Bull Yanks”. The letter C was used to designate the class, which had previously been assigned to a class of tank locomotives with a 0-6-0T wheel arrangement that had been retired in the same year.

In contrast to the Ec, the class C received only a simple two-cylinder engine, which further reduced the production costs. From 1908 they received a trailing axle, which led to the 4-6-2 wheel arrangement and the renaming to class Ca. Another series of ten locos was built directly in the Midland Railway Workshops in 1915 as 4-6-2. With the installation of a superheater, they became the class Cs from 1929. The WAGR used the last locomotives until 1961. Some locomotives had been used in industry since the early 1950s, and these were also scrapped in 1964.