In April 1896, the WAGR placed an order with R&W Hawthorn Leslie & Co for four 4-6-2T locomotives.

[1] The 1895 built locomotives had different shaped cab windows and side tanks.

In 1905, Q140 was rebuilt with a new boiler and converted to 4-6-4T configuration with water and coal capacity increased to make it suitable to operate on the Upper Darling Range railway, Q141-Q143 followed in 1909.

[2] They operated branch line services on the Mundaring, Mundaring Weir, Pinjarra-Holyoake and Upper Darling Range lines as well as on the Eastern Railway to Northam and South Western Railway to Bunbury.

It was reused in the 1990s when the Westrail Q class diesel locomotives entered service.