Bison concrete armoured lorry/mobile pillbox:

Bisons were produced in Britain during the invasion crisis of 1940-1941. Based on a number of different lorry chassis, it featured a fighting compartment protected by a layer of concrete. Bisons were used by the Royal Air Force (RAF) to protect aerodromes and by the Home Guard. They came in multiple forms. Many were old and some dated from the First World War period, one had even seen service as a fire engine and some had not even been converted from solid to pneumatic tyres. With a variety of chassis to work on, Bisons inevitably varied in detail, but were made in three distinct types:
Type 1 was the lightest. It had a fully armoured cab and a small armoured fighting compartment roofed with canvas.
Type 2 had an armoured cab roofed with canvas and a separate fully enclosed fighting compartment resembling a small pillbox on the back.
Type 3 was the largest and heaviest. It had a contiguous cabin and fighting compartment completely enclosed in concrete armour.


