ified just before the outbreak of the Second World War, the A20 (its General Staff specification) was to supplement the Matilda II and Valentine infantry tanks. In accordance with British infantry tank doctrine and based on the expected needs of attacking a fixed defensive line, crossing wide trenches, possibly shell-cratered ground similar to First World War trench warfare it was to be immune to the current German 3.7 cm Pak 36 anti-tank guns and carry an unditching beam. A general outline produced by Woolwich Arsenal was expanded by Belfast shipbuilders Harland & Wolff with advice from the Department of Tank Design. The General Staff had proposed that it was armed with two QF 2 pounder guns, each located in a side sponson with a coaxial Besa machine gun. A third Besa and a smoke projector would be fitted in the front hull. To reduce weight the specification was revised to prefer a maximum armour to the front of 60 mm – sufficient to protect against ordinary shells from the German 37 mm gun. Outline drawings were produced by Woolwich Arsenal based on the A12 Matilda turret – the Director of Mechanisation opposed a turretless design – and the engi