In 1935 AG Watson ordered a further fifty Class 19B locomotives from North British which were fitted with Rotary Cam poppet valve gear and became Class 19C. When further engines were required in 1937 the then Chief Mechanical Engineer, WAJ Day, dispensed with the poppet valves in favour of piston valves and the new locos were classified 19D.The first examples were built by Krupp with subsequent units being constructed by Borsig, Skoda, Krupp, Robert Stephenson & Hawthorn and North British.. The final fifty being fitted with Vanderbilt “torpedo” tenders and six wheel “Buckeye” bogies. For some reason twenty of the locomotives built by Krupp were fitted with domeless boilers. This was not the end of the story as the success of the design led to other railway administrations in Southern Africa ordering similar locomotives. Twenty one locomotives were purchased by Rhodesia Railways from Henschel, six were built by North British for the CFB (Benguela Railway) in Angola plus four more in unsuperheated form for Wankie Colliery. Henschel built another two for Nkana Copper in Zambia but these were later sold to Rhodesia Railways. In total 268 locos were built to the 19D design.

The four locomotives in the Sandstone Collection are all ex Lorraine Gold Mine in Welkom.
The 19D weighs nearly 130 tons with a short tender and 157 tons with the Vanderbilt tender. The lengths being 67 feet (20,42m) and 86 feet (26,21m) respectively.