LMS Fowler

The LMS Fowler 2-6-4T was a series of 125 outside-cylinder 2-6-4 side-tank locomotives designed by Henry Fowler and built at Derby Works from 1927, representing the first large 2-6-4T tank locomotive class in British service and establishing the wheel arrangement that Stanier would develop into one of the most successful British tank locomotive families of the 1930s–50s. The Fowler 2-6-4T was a significant step forward from the earlier inside-cylinder suburban tanks: the outside cylinders and larger boiler gave substantially more power for the heavy suburban and semi-fast passenger services on the former-Midland main lines and the LTS routes out of Fenchurch Street.

Fowler's design used two outside cylinders, a parallel boiler — rather than the taper boiler that Stanier would introduce from 1935 — and 5 ft 9 in coupled driving wheels suited to the semi-fast suburban and outer-suburban services the class was intended for. The six coupled wheels gave good adhesion for starting heavily loaded suburban trains and the side tanks provided adequate water capacity for the extended outer-suburban runs on the Midland Division and LTS lines.

The Fowler 2-6-4Ts gave sound if not exceptional service on LMS suburban and secondary duties. Stanier's development of the design from 1935 — replacing the parallel boiler with his own taper boiler and improving the steam circuit — produced a significantly better locomotive in the Stanier 2-6-4T. Several Fowler 2-6-4Ts survived into the BR era; none was preserved.