Between 1884 and 1886, Worsdell had 40 tank locomotives built for the Great Eastern Railway for passenger service, which were called class M15. This first batch got Joy valve gear and due to their high consumption, they got the nickname “Gobblers”. Holden made 120 more between 1903 and 1909, which received Stephenson valve gear for lower fuel consumption. Many were fitted with a condensing gear for London traffic.

Locomotive Magazine, February 1913

Between 1911 and 1920, 32 of the original batch were rebuilt to class M15R by adding a new boiler with a higher pressure and by installing Stephenson valve gear. At the LNER, the unrebuilt locomotives became the class F4 and the rebuilt ones became the F5. The first locomotives had already been withdrawn from 1913, but some F4s remained in service until 1956. In 1949, seven F5 were equipped with push-pull apparatus. The F5 was only withdrawn between 1955 and 1958.