From the release:
The Armadillo was an armoured fighting vehicle produced in Britain during the invasion crisis of 1940-1941. Based on a number of standard lorry chassis, it comprised a wooden fighting compartment protected by a layer of gravel filling the walls of the ‘fort’ and a driver’s cab protected by mild steel plates. Armadillos were used by the Royal Air Force (RAF) to protect aerodromes and by the Home Guard (making it an ideal addition to our new Dad’s Army Home Guard Platoon!).