Guy started production of the Humber, but as it was to be dedicated to producing light tanks, production was moved to Rootes Group and Karrier Motors Limited. Guy did provided armored hulls and turrets.
After production started the armored car received the Humber Mk I name.
- Humber Mk I: 500
- Humber Mk II:
- Humber Mk III:
- Production started in early 1942
- Humber Mk IV:
- Total: 5,400
- Manufacturer: Guy, Rootes Group, Karrier Motors Limited at Luton
- Armoured Car Mk I Fox I: 200