The number to be produced was subject to fluctuation as the War Office vacillated in their demand; in July 1938, it requested that 70 of the tanks be produced, then increased the request to 120 after a three-day conference in November. Production was to begin in July 1940, but meanwhile the War Office temporarily returned to its original order of 70 before increasing the number to 100. The number further increased to 220 after Metropolitan Cammell Carriage and Wagon, a company part owned by Vickers-Armstrong that would be producing the tanks, indicated it had already ordered armour plating for that many tanks.