It was designed by John D. Tilney, the Locomotive Superintendent of the Eastern System, to be able to use the low-grade local coal with its high content of incombustible matter.

[1][2] In 1883, the extension of the Cape Government Railways (CGR) Eastern System's line from Queenstown reached Sterkstroom and passed through the Stormberg coalfields, where the Molteno and Cyphergat collieries were operating.

The most significant of these experiments involved modifying the boilers and frames to accommodate oscillating firebars and larger fireboxes.

This peculiar tender wheel arrangement appeared in South Africa on only one other occasion, eighteen years later on the Baldwin-built Zululand Railway Company contractor's locomotive in Natal.

[1] Like the Neilson-built 4th Class 4-6-0TT of 1882, these locomotives were built with Joy valve gear, but they had smaller coupled wheels of 38+1⁄2 inches (978 millimetres) diameter.

[1] The locomotives gave good results in service, but were difficult to fire due to their very long and narrow grates.