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This model is the AHI Scammell Mechanical Horse and Trailer in red and grey. It comes in its original AHI branded box marked "Open Trailer Truck". This is a copy of the MB10-a Scammell Scarab Mechanical Horse and Trailer.
The tractor unit is a single piece metal body, 34mm in length to which is attached the rear trailer casting, 38mm in length. The tractor casting has representations of the bumper, hood badge, doors, and windows. The trailer casting is of a simple drop-side trailer. There is no glazing. The original wheels are grey plastic and attached to steel axles with a domed end and a crimped end. They are held to the body by means of short columns or cast areas through which the axles pass.
There is no base plate as such and this cast toy has no manufacturer's marks but does have country of origin (JAPAN) cast on the trailer.
I do not know exactly when this item was issued but it would have been during the 1950s and 1960s.