After the Class C with a 4-4-0 wheel arrangement and 6 ft 7 in wheels, the Shanghai-Nanjing Railway ordered four more locomotives that were to have even larger wheels. Using a boiler that was largely the same as that of existing classes of the company, one driving axle now had to be sufficient. Despite this, the boiler was the largest ever to be found on a British-made single-driver locomotive.

The engines were intended for express traffic as part of a large trade fair in Nanjing and should be up and running within 45 days of receipt of the order. Despite the national mourning for the death of King Edward and the Pentecost holidays, the time had come after 47 days. Their special position was underlined by the fact that they were painted in a bright yellow instead of the usual green.