In 1914 the South African Railways placed fifteen Class MC1 Mallet articulated compound steam locomotives with a 2-6-6-0 wheel arrangement in service.

[1][2] Orders for an improved version of the Class MC were placed with the North British Locomotive Company in 1913.

When the fifteen locomotives were delivered and placed in service in May 1914, they were designated Class MC1 and numbered in the range from 1634 to 1648.

Improvements consisted mainly of 1⁄2 inch (13 millimetres) larger diameter high-pressure and low-pressure cylinders and a redesigned boiler which included a superheater instead of the saturated steam boiler of the Class MC.

The result was a much better performing locomotive with an increased tractive effort brought about by the larger cylinders.