By reducing the driving wheel diameter from 75 to 62.5 inches, George Whale, superintendent at the LNWR, developed a locomotive for mixed service from his Experiment class. The resulting class reached a total of 170 and was officially referred to as “19in Express Goods,” a reference to the cylinder diameter and its primary intended use in front of express goods trains.
Because of their origin they were also called the “Experiment Goods Class”. They were classified by the LMS into power class 4F and were withdrawn from service from 1931. British Railways only took over three locomotives, which disappeared by 1950. 