[4] In early 1938, a number of different 4×4 chassis from British and foreign manufacturers had been tested to see which was the best for development of a new line of armoured cars to replace the older designs in use.

The vehicles successfully completed troop trials and from 1939–1940 a further 101 of the armoured cars – initially designated "Tank, Light, (Wheeled) Mark I" – were produced.

[4] To that end, they developed the necessary techniques including rotating jigs, which meant the bodies and turrets could be produced quicker and cheaper.

[1] The vehicle had a welded hull (making it the first British armoured car with an all-welded construction) with a sloped glacis plate.

[3] The body of the Guy vehicle formed the basis of the later Humber Armoured Car, which employed a new chassis.