Rising passenger numbers due to the gold rush prompted the WAGR to order tank locomotives in the 1890s. These were used in suburban service around Perth and in the Kalgoorlie area. They had the wheel arrangement 4-4-4T for good running characteristics in both directions and weighed only 44 tons. The drivers measured four feet and the cylinders were 15.5 by 21 inches. Combined with a boiler pressure of 160 psi, this resulted in a starting tractive effort of 14,300 pounds. 

The first five were built by Neilson & Co. in 1896. 15 more had followed from Nasmyth, Wilson & Co. and twelve from Robert Stephenson & Co. by 1901. The total number was increased to 42 in 1907 and 1908 when the Midland Railway Workshops rebuilt ten 2-8-0 class O which had been built by Neilson & Co. in 1896. The first ones were withdrawn in the forties when the Dm and Dd class tank locomotives were introduced. Others were replaced by ADH diesel multiple units. The last one was withdrawn in 1961 and today N201 is on display in the Western Australian Rail Transport Museum.