The Great Central class 9J consisted of 174 0-6-0 freight locomotives designed by John G. Robinson. Production ran from 1901 to 1910 at the GCR's own Gorton Works and four commercial manufacturers. They were nicknamed “Pom-Poms” because of their exhaust sound, which crews said was reminiscent of the quick-firing Maxim cannon of the same name from the end of the 19th century. In practice, they were not only used in freight service, but also in all types of trains, including express trains.

As early as 1909, the first new locomotive was built with the Robinson superheater. Over the next 30 years, many more were retrofitted with it. At the LNER they became the J11, and after various modifications they were divided into J11/1 to J11/5. From 1942 onwards, Thompson equipped some locomotives with piston valves, which then often reached 60 mph (97 km/h). British Railways took over the entire class, which was ultimately phased out by 1962.