The idea for a new class of two cylinder, 4-6-0, mixed traffic locomotive on the Great Western Railway came from George Churchward, Chief Mechanical Officer at the time, in the years preceding the First World War. His proposal envisaged combining the standard Swindon No.1 boiler with driving wheels of 5’ 8” to deliver a combination of good pulling power and good acceleration, vital in the design of an efficient mixed traffic locomotive. For any number of reasons, and despite his other proposals all coming to fruition, the design was not pursued and it was to be the 1930s before the idea was revived.

Charles Collett had replaced Churchward as CME in 1922 and in 1936, under pressure from the GWR’s Operating Department, he sought to replace Churchward’s ageing 4300 class 2-6-0 locomotives with a new design, based on Churchward’s original idea for a mixed traffic locomotive. The GWR 6800 ‘Grange’ class utilised a number of parts from the rapidly withdrawn ‘4300’s in their construction, notably the driving wheels and motions and the first example, No.6800 Arlington Grange, was turned out from Swindon on August 27, 1936. A further nineteen locomotives had entered traffic by the year end, followed by forty in 1937 and another twenty in 1939, but the onset of the Second World led to the postponement, then cancellation, of the building programme.