A problem with the Cape Government Railways mainline locomotives of the 1870s was the small driver diameter of less than 40 inches. On passenger trains in particular, this led to high wear if they were ran at higher speeds for a longer period of time. In addition, the range of the tank locomotives mostly used was too small for newly opened lines in sparsely populated areas.

The solution was a tender locomotive with a 4-4-0 wheel arrangement and a wheel diameter of 48 inches. First, in 1879, the Avonside Engine Company delivered two locomotives each for the western and eastern networks, which received the numbers W25, W26, E8 and E9. The following year Neilson & Co. added six more for the west and five more for the east, bringing the total to 15.

With the help of these locomotives, the Karoo semi-desert could now also be opened up with fast passenger trains. An average speed of 34 mph was reached on the 339 miles long route from Cape Town to Beaufort West, which was a record for South Africa. When the South African Railways were founded in 1910, the locomotives, which were now classified as class 1, were classified as obsolete. So they became class 01 and got a zero prefixed to their running number. The nine locomotives still in existence at that time were all retired until 1915.