When the Union of South Africa was established on 31 May 1910, the three Colonial government railways (Cape Government Railways, Natal Government Railways and CSAR) were united under a single administration to control and administer the railways, ports and harbours of the Union.
When they were assimilated into the South African Railways (SAR) in 1912, the five saturated steam locomotives were designated Class 10A, while the five superheated steam locomotives, numbered in the range from 670 to 674, were designated Class 10B and renumbered in the range from 752 to 756 [REF].