Cruiser Mk II The Tank , Cruiser , Mk II ( A10 ) , was developed alongside the A9 , and was intended to be a heavier , infantry tank version of that type . In practice it was not deemed suitable for the infantry tank role and was classified as a " heavy cruiser " . History and specifications . The A10 was developed by Sir John Carden of Vickers in 1934 by adaptation of his A9 design . The A10 specification called for armour of up to 1 inch standard ( the A9 was 14mm ) ; a speed of 10 mph was acceptable . The two sub - turrets present on the A9 were removed , and extra armour bolted onto that already present on the front and sides of the hull , along with all faces of the turret , providing approximately twice the armour in most areas . The A10 was two tonnes heavier than the A9 , but used the same 150 bhp engine , and as a consequence the tank ' s top speed was cut from 25 mph to 16 mph . The turret armament consisted of a QF 2 - pounder ( 40mm ) gun and a coaxial . 303 Vickers machine gun . For the production version there was a 7 . 92mm BESA machine gun mounted in the hull in a barbette to the right of the driver . This was added to give extra firepower but at the expense of simplicity - the Vickers and the BESA using different ammunition . The tank had a total crew of five ( Commander , gunner , loader , driver and hull machine gunner ) , and there was no separation between the driver ' s compartment and the fighting compartments . The prototype ( " Tank , Experimental A10E1 " ) was completed in 1936 , a few months after the A9 prototype . Carden had died in an air crash in 1935 and development was slower than expected . In 1937 the A10 was dropped as an infantry support but in 1938 it was decided to produce it as a " heavy cruiser " . The A10 was accepted for service - initially as " Tank , Cruiser , Heavy Mk I " and then " Tank , Cruiser A10 Mk 1 " and finally " Tank , Cruiser Mk II " . Production was ordered in July 1938 . Total production was 175 vehicles including the 30 CS versions ( see below ) , 45 were built by Birmingham Railway Carriage and Wagon Company , 45 by Metropolitan - Cammell , 10 by Vickers . In late 1939 another order was placed with Birmingham Railway Carriage and Wagon Company , this time it was a larger order of 75 vehicles . - entering service in December 1939 , but was something of an oddity - it had been intended to sacrifice speed for armour like an Infantry tank , but was still relatively poorly armoured , and was , as a result , not effective . Combat history . A number of Mark IIs were part of the British Expeditionary Force ( BEF ) sent to France in the early stages of World War II . Their cross country performance was recorded as poor , but they were still used later in North Africa at the defence of Tobruk in 1941 , where reliability and suspension performance in the desert conditions was praised . Sixty worn out examples were taken to Greece by the 3rd Royal Tank Regiment and , although they performed well against the German tanks , over 90 % were lost due to mechanical breakdowns as opposed to enemy action ( mainly lost tracks ) . Variants . Tank , Cruiser , Mk II ( A10 Mk I ) . Classified as a ' heavy cruiser ' and 31 were sent to France with the 1st Armoured Division , but performed poorly in the following campaign . Also served in the North African Campaign until late in 1941 . Tank , Cruiser , Mk IIA ( A10 Mk IA ) . The coaxial Vickers machine guns were replaced with BESA machine guns . Armoured radio housing added . Tank , Cruiser , Mk IIA CS ( A10 Mk IA CS ) . Had a 3 . 7 " ( 94 mm ) howitzer in the turret instead of the 2 pdr . The standard ammunition load was 40 rounds smoke , and a few HE shells . The CS denotes Close Support . This weapon was derived from a World War I field howitzer . It was not related to the 3in howitzer used in later British tanks in World War II , which was itself replaced by a 95mm howitzer in the later versions of the Churchill infantry tanks and all CS versions of the Centaur and Cromwell cruiser tanks . British doctrine was that the CS tank was to provide smoke cover in advances or retreats and hence many more smoke rounds were carried than HE .