6 Class

The Midland Railway 6 Class was Samuel W. Johnson's first 0-4-4 suburban tank design for the Midland Railway, built at Derby Works from 1875. Johnson had arrived at Derby in 1873 from the Great Eastern Railway, where he had introduced the 134 Class suburban tanks, and the 6 Class represented a direct continuation of that design philosophy applied to the MR's rather different suburban requirements.

The Midland Railway's suburban traffic in the mid-1870s was concentrated around London (St Pancras), Birmingham, Leeds, and Sheffield, and the 6 Class was intended to provide a versatile and economical tank engine capable of working the frequent stop-and-start services on these routes without the operational complications of a tender locomotive. Johnson specified the 0-4-4T wheel arrangement — two coupled driving axles followed by a trailing bogie — which distributed the weight well and gave good tracking at moderate suburban speeds.

The locomotives were built at Derby and carried the Midland Railway's characteristic crimson lake livery with black and yellow lining. Johnson went on to produce numerous subsequent suburban and branch tank designs for the MR, and the 6 Class represented the foundation on which those later, more developed classes were built. None was preserved.