engine to be cheaper. It was accepted as an interim design for limited production as the Cruiser Tank Mark I. It was expected to be replaced by a Christie suspension design. From 1937–1938, 125 A9s were built. The A9 was lightly armoured but capable of and carried a highly-effective 2-pounder anti-tank gun. The Cruiser Mk II (A10), was designed by Carden as an infantry tank, built to the same design with added armour for of protection. It was insufficiently armoured for the role but as a "heavy cruiser", it was put into production in July 1938 as another interim design. It had the same gun as the A9, was the first to be equipped with the Besa machine gun and 175 Mk IIs were produced by September 1940. Experience with the A9 during the Battle of France in 1940 revealed shortcomings, including inadequate armour and a lack of space for the crew, but it saw useful service in France, the Western desert and Greece in 1941. Orders for the Mk I and Mk II Cruisers were limited, for an advanced and faster cruiser tank which would incorporate Christie suspension designed by J. Walter Christie and have better armour. In 1936, General Giffard LeQuesne Martel, a pioneer in tank design who had published works on armoured warfare and pioneered the lightly armoured "tankette" concept to enhance infantry mobility, became Assistant Director of Mechanization at the War Office. Later that year, Martel had watched Soviet tanks at the Red Army's autumn manoeuvres including the BT tank, which they had developed from Christie's work. He urged the adoption of a tank that would use the suspension system and also follow the Christie practice of using a lightweight aircraft engine such as the Liberty L-12 engine or a Napier Lion. The government authorised purchase and licensing of a Christie design via the Nuffield Organization. The tank A13 E1 was rudimentary and too small for British use but the Nuffield suspension was most effective and this became the basis of the Cruiser Mk III (A13). Following testing of two Nuffield-built prototypes (A13E2 and A13E3), the A13 was ordered into production and 65 were manufactured by mid-1939. The Mk III weighed , had a crew of 4, a 340 hp engine which gave a top speed of and was armed with a 2-pounder (40 mm) gun and a machine gun. When it was introduced in 1937,