AEC had already built a 4 x 2 lorry, also known as the Matador (all AEC lorries received 'M' names).
The Matador was distinctive with its flat fronted cab with gently curved roof, wheels at the corners and a flat load carrying area covered by a canvas or tarpaulin tilt. The cab was made from Ash and clad in steel. It was equipped with a winch (7-ton load in its case) like all artillery tractors. The O853 provided the basis for the 'Dorchester' Armoured Command Vehicle.
AEC also produced a larger 'Marshall' 6x6 vehicle (model O854) based on the 4x4 Matador which were generally, if not officially, also called Matador. The O854 also provided the basis for an Armoured Command Vehicle, the O857.
This is a paper model, you can download this papercraft from here: 1:100 WWII AEC Matador Ambulance Truck Free papercraft download