The O4s were added to when the LNER purchased 273 ex-Railway Operating DivisionROD 2-8-0s to the same design between 1923 and 1927. Meanwhile, the 19 GCR Class 8M (LNER Class O5) were rebuilt as O4 standard during the 1920s and 1930s. 92 O4 locomotives were requisitioned by the War Department during World War II and shipped during late 1941 for operation in the Middle East.
The O4 class were used to haul heavy freight trains throughout the LNER system. 329 engines remained in operation at 1 January 1948.
Sub-classes
The LNER rebuilt many, allotting them into eight subclasses.
Sub-class details: