The class E of 1902 was the first Pacific locomotive of the Western Australian Government Railways. It must not be confused with the class E double Fairlie of 1879 and the class E diesel of 1957. Its origin can be traced back to the requirement for a new long-range express locomotive that was able to climb mountains like the Darling Scarp, while having an axle load that wasn't too high.

The first 45 locomotives were ordered in 1900 from Nasmyth, Wilson & Co. and from Vulcan foundry. As British manufacturers didn't have enough capacities to deliver more, 20 class Ec Vauclain Compounds were ordered from Baldwin. In 1911, another batch of 20 class E locomotives was ordered from North British.

In 1924 and 1925, a total of 61 of the 65 locomotives were superheated and designated class Es. In 1934 two underwent a weight reduction program to be used on lines with a low permitted axle load. These were called class Ea, but were converted back five years later. The majority of class E was withdrawn in the fifties and the last one operated until 1963. 308 was preserved and is located at the Western Australian Rail Transport Museum.