Regiment (Princess Alice's Own). The was the only SAR locomotive to be honoured in this way by the armed forces. The Class 21 was scrapped in 1952 after only 15 years in service. During its time in service, it was equipped with smoke deflectors. Neither the Class 21 nor the aborted Class 22 design was repeated in either its original or modified form, leaving the impression that they represented advanced thinking which appears to have been considered as too far and too fast by Watson's successors. When it was scrapped at the Pretoria shops, its Watson Standard no. 3B boiler was repaired and retained as a spare for use on the other locomotive classes equipped with this boiler model. Its Type FT tender was allocated to Kroonstad Loco as a spare tender for use on Class 15F locomotives, since all the Class 15Fs shedded at Kroonstad at the time were fitted with mechanical stokers. The Type FT could work coupled to these engines because they used the same type of Watson Standard no. 3B boiler and firebox arranged for mechanical firing as the Class 21. The tender was rarely used, if ever, since it had a smaller coal and water capacity than the Type JT tender normally fitted to the Class 15F. The aborted Class 22 A design for a Class 22 steam locomotive, Watson's final design, was submitted at about the same time. The proposed was also to have a 2-10-4 Texas wheel arrangement, but was to have been a heavy mainline version of the Class 21 with an axle load of , the heaviest that current SAR track could bear on its mainline rail. It was to have been a massive machine with larger coupled wheels, a larger grate and the larger Type EW tender which was later to be used with the Class 23 locomotive. If this engine had been built, it may have been one of the world's most outstanding locomotives. The proposed boiler pressure was , a figure never attained on the SAR, and its anticipated tractive effort of at 75% of boiler pressure would have made it capable of handling loads of on the coal run from Witbank to Johannesburg with comparative ease. The design was a compromise between a 2-8-4 passenger class with coupled wheels and a freight locomotive with coupled wheels. At the time, however, the demand for general utility locomotive types