The British Army evaluated the Mark E, but rejected it, apparently due to questions about the reliability of the suspension. Vickers then started advertising the design to all buyers, and soon received a trickle of orders eventually including USSR, Greece, Poland, Bolivia, Siam, Finland, Portugal, China and Bulgaria. Thailand purchased 36 Vickers Medium Dragon Mark IV, and QF 2-pounder naval guns were added to turn them into self-propelled guns used in the 1940-41 Franco-Thai War. Vickers built a total of 153 (the most common figure) Mark Es.