These locomotives were built to a standard Nasmyth Wilson design for export, and had double-skinned cab roofs for work in tropical climates.

The locomotives, numbered as NZMRC NO's 1–5, were responsible for running all trains over the Midland Railway between Reefton, Stillwater and Lake Brunner, as well as running NZMRC trains over the NZR line between Stillwater and Greymouth.

Two of the withdrawn locomotives were sold for industrial service; LA 311 was sold to the Auckland Farmers Freezing Company in 1920 and worked as a shunting locomotive at their Moerewa works between 1920 and 1934, while LA 314 was sold to the New Forest Sawmilling Company at Ngahere where it worked as the mill's yard engine transferring wagons between the NZR station and the sawmill between 1926 and 1950.

The remains of LA 312 were salvaged for preservation in 2006 and are now in storage pending restoration to working order.

The conversion, classified by the NZR as the LA class, did not address the limited fuel capacity, and all further rebuilds were rebuilt as 4-4-2Ts.