The London Midland and Scottish Railway (LMS) Fowler 4F is a class of 0-6-0 steam locomotive designed for medium freight work. They represent the ultimate development of Midland Railway's six coupled tender engines.
The 4F was based on the 197-strong Midland Railway 3835 Class of 1911, with only a few modifications, primarily the adoption of left-hand drive in favour of right-hand drive. They originally had been designed by Henry Fowler, who from 1925 became CME of the LMS.
Midland Railway locomotives were notorious for their short axle-box bearings, which were prone to overheating. Why this poor design feature was perpetuated is a complete mystery but, unfortunately, the LMS 4F inherited it.
The LMS constructed 530 of the locomotives between 1923 and 1928, numbered sequentially from where the Midland engines left off from 4027. A further 45 examples were reluctantly authorised by William Stanier in 1937 at the behest of the operating department.
