The concept of the Mechanical Horse tractor unit with an easily detached articulated trailer was conceived in the early 1930s by Napier & Son. It has one front wheel in the midline. The London and North Eastern Railway had approached Napier for an answer to the problem of replacing horses for local haulage purposes, while retaining the flexibility of changing the wagons and the maneuverability of the horse and wagon. These vehicles are often known as "Snub-nose Trucks" or "Snub-nose Lorries" because of the round hood in front of the cab.
