In the mid-1920s, with train load sizes increasing to and from the South West, the Great Western Railway were faced with the need for even more powerful locomotives, capable of hauling the heavy expresses at an average speed of 60 mph. The main routes were limited to a 20 ton axle weight though, so a number of the Great Western’s routes had to be upgraded, including the strengthening of some bridges, before the Great Western’s General Manager, Sir Felix Pole, would give his Chief Mechanical Engineer, Charles Collett, permission to proceed with the design and construction of a