Although Churchill's plans for the standardisation of the Great Western motive power was centred entirely upon a two-cylinder engine, with inside Stephenson's link motion, there is no doubt that the locomotive design by which he will be best remembered is that of the four-cylinder Walschaert valve-geared 'Stars'. As finally developed, from the Atlantic North Star of 1906, with the 'scissors' valve gear, to the 'Princesses' of 1914, superheated and with 15 in. diameter cylinders, they proved capable of astonishing feats of weight haulage and high speed, at very economical rates of coal consumption.