These Madras & Southern Mahratta locomotives were basically based on the design of the Indian Standards Committee, but as an innovation they were operated with superheated steam and had a slightly reduced boiler pressure. The superheater was of the Schmidt design and had a proportionately larger heating surface than most British-built locomotives. After the four Stephenson locomotives from 1910, a total of 21 from Kitson and Armstrong-Whitworth came in 1919 with slightly altered boiler dimensions and a smaller superheater. Other, almost identical ones went to the Bombay, Baroda & Central India.