In 1915 the British Army started to use armoured cars in India, particularly on the North West Frontier, to relieve troops needed elsewhere. They proved so successful that this soon became standard policy. Shortly after the war the Indian Government purchased 16 Rolls-Royce cars to a new design but these proved so expensive that subsequent orders were placed with Crossley Motors in Manchester who made a tough but cheap 50hp IAG1 chassis. Substantial numbers of these cars were supplied between 1923 and 1925.
The body design, which was very similar to the Rolls-Royce version and built by Vickers at Crayford, had a number of interesting features. These included a dome-shaped turret, with four machine-gun mounts, which was designed to deflect rifle shots from snipers in ambush positions in the high passes. A clamshell cupola surmounted the turret for the commander, while side doors opened opposite ways on either side so that a crew member could dismount safely under fire. The crew area was lined with asbestos to keep the temperature down and the entire body could be electrified to keep large crowds at bay.
By 1939, when the Royal Tank Corps in India had handed most of its equipment over to the Indian Army, the Crossleys were worn out. The bodies were then transferred to imported Canadian Chevrolet chassis, with pneumatic tyres, and in this form served with Indian forces in the Middle East in the early years of the war.
You can imagine in an early Very British Civil War scenario in the early 1920s, the Vickers factory making these armoured cars available to one of the armies for fighting the civil war. You would have to think about some rules for allowing the entire body could be electrified and the impact that this would have in games.
The Vickers Crossley Armoured Car was also exported to Japan who made use of them in China.
Company B make a 1/56th scale metal and resin version which is available.
Whilst you can get a 3D printed version in 15mm from Shapeways.