"Closely defined roles"

In the early 1930's, British tank policy produced the medium tanks, the light tanks, and the carriers. The light tanks and carriers were produced because they were cheap, and were an obvious improvement to the limited mobility of the medium tanks. The Medium Mk.III were an attempt to improve on that, but they were too expensive for the times, so the next phase was to follow the path that light tanks and carriers started. There were to be highly specialized vehicles, rather than general purpose armored fighting vehicles. Earlier policy was more like naval policy, in some ways, in that they produced heavy and light vehicles, with the idea that each had their own utility, and the smaller vehicles were faster and were useful in more of a cavalry role for scouting. They were equipped with machine guns, as that seems a suitable weapon for their size. The earlier medium tanks all had 3pdr guns (47mm) with a rather poor anti-armor performance. The new guns, with higher velocity but lighter shot were the 40mm 2pdr. That piece was to be used as the anti-tank gun and for the tank weapon. A very few tanks were equipped with 3in mortars or howitizers of low performance. They were produced because of the acknowledgement that tanks might need to fight something besides other tanks. So, the new policy produced "heavy" and "light"cruiser tanks for the tank fighting role. The slowest were only capable of infantry tanks speeds (the A.10 Cruiser Mk.II and IIA), namely 15 mph, maximum. The faster were the Christy-inspired A.13 Cruiser Mk.III, Mk.IV, and Mk.IVA, which were capable of a governed speed of 30 mph. Without a governor, they could make 40 mph. It was only after hard experience fighting the Panzer Mk.III and Mk.IV that the British began to realize that they had problems. Their savior was the more general purpose, American-built medium tanks, such as the Grant and Sherman. The Sherman became the almost universal Allied tank, because of its huge production run. The British made do with upgunning their existing tanks and spawning new generations of cruiser tanks, with larger guns and heavier armor, such as the Cromwell and Comet. Their best tank was too late for combat, the ultra-modern (for the times) Centurion, which set the pace for modern tanks, being vastly superior to the Sherman.