Mk IIA: 29 constructed at the Royal Arsenal, Woolwich. Two fuel tanks. No 1 Mk II turret has air louvres on each side at the top. The sliding roof hatch of the No 1 Mk I was replaced with a more secure arrangement of a folding hatch with two doors. Early light tanks were first fitted with Meadows six-cylinder engines but these were later replaced by Rolls-Royce power units. The turret, which is turned bodily by the gunner, contains a water-cooled Vickers machine-gun. The driver, who sits below and in front of the gunner is also located alongside the engine, so conditions inside are warm and noisy. These light tanks served with the Royal Tank Corps in Britain, the Middle East, and India. Many were still in service when the Second World War began.