Vickers created the Light Tank Mk VII as a private venture in 1937. The Light Tank Mk VII was adopted by the British Army in 1938. Production started in 1940, but was halted due to the vulnerabilities of light tanks on the battle fields of Europe. Production started back up in 1941 when it was decided the vehicle could be used by the airborne forces.
Originally called the Purdah or PR tank it was renamed Tetrarch in 1943.
The hull did not extend over the tracks. Smoke discharges on each side of the turret. Some vehicles had a spare gas tank on top of the rear deck.
There was a square box that covered the driver's head and shoulders. This could be swung open to allow the driver better visibility. No cupola for the commander and he also was the loader for the main gun.
The turret was in the center and could hold the commander and the loader.
The tracks were meant to be removed so that the tank could travel faster on roads. It used skid steering (developed by Leslie Little) which involved pivoting the wheels to make the tracks flex. The center wheels would move in or out to bow the track. It was controlled by the steering wheel. However, if the driver needed a very sharp turn then he needed to also use 2 levers and apply the brakes.
The coaxial MG was fitted to the same mounting as the main armament and rotated and elevated with it.
Some vehicles were fitted with the Littlejohn adaptor to increase the muzzle velocity of the 2 pdr.