To expand their Mallet fleet inherited from the NGR, the SAR ordered ten locomotives of the new class MC in 1912. As opposed to the NGR Mallets which were now designated classes MA and MB and had been built by ALCO, the ten MC locomotives were built by North British. While similar in overall dimensions and power, some details were executed after British practice.
The primary task was, like the MA and MB, heavy coal trafic between Estcourt and Highlands. Later some came to the Cape Western System as bankers and others hauled coal in Witwatersrand. Built with saturated boilers, 1612 and 1615 were the only ones which later got new superheated boilers. All were finally withdrawn in 1933.