In the desperate days after Dunkirk, the British army was desperately short of material, especially armored vehicles. One of the many improvised solutions were the "Bison" trucks - just the thing for gaming
Unternehmen Seelöwe "Operation Sea Lion" - the planned German invasion of Great Britain.
Designed by an engineer of the Bison construction company, they consisted of concrete boxes mounted on top of old trucks. Too slow to be used as fighting vehicles, they served as mobile pillboxes, for example to defend airfields against paratrooper assault.
Wikipedia has more information about the original
This item consists of 5 truck model of 3 different designs.