Before being selected, the company had already been in the process of developing designs for a glider which would carry a single Mk VII 'Tetrarch' light tank. The design was a low-wing aircraft designed so that the tank driver also functioned as the glider pilot, and flew the glider from his seat in the tank through a series of internal modifications to the tank. The idea behind the design was to save on specially-trained glider pilots and allow the tank to be brought into action as soon as the glider landed; surviving illustrations of the design show the tank encased in the glider's fuselage but with the turret outside the airframe, possibly so that it could engage targets as it landed. However, the design was considered to be impractical, both by the company and the War Office, and a more conventional design was finally arrived at in a joint meeting between the two in January 1941. It called for a glider which would be constructed primarily out of wood capable of carrying a Tetrarch light tank or two Universal Carriers with a combined maximum weight of approximately ; a surviving requisition form from the Air Ministry to GAL confirms a cost of £50,000 per glider. By early February 1941 the basic design for the glider had been completed by the company's chief designer, and had been designated the GAL. 49 with the service name 'Hamilcar'; the name came from the Carthaginian general Hamilcar Barca.