The design of these locomotives was attributed to the Metropolitan Engineer John Fowler, but the design was a development of a locomotive Beyers had built for the Spanish Tudela & Bilbao Railway, Fowler only specifying the driving wheel diameter, axle weight and the ability to navigate sharp curves.

To assist local industry, a contract for eight was awarded to the Atlas Engineering Works, Haymarket and delivered in 1881–1882.

88 was converted at Eveleigh Railway Workshops to a 4-4-2T tank engine for Sydney suburban service with a further 19 following by 1902.

In an attempt to prevent cinders blocking the lower boiler tubes between cleanings in December 1956 an extended smokebox was fitted to 1219 with 1243 similarly modified in the 1960s.

[4][5][6] Three have been preserved: Media related to New South Wales Z12 class locomotives at Wikimedia Commons