The "Austin Duck" was originally a British Alvis Stalwart. The Stalwart was manufactured by the Alvis Company; it is a vehicle / vessel that is very similar to the DUKW built by General Motors for the United States Army. The vehicle can be driven in either four-wheel drive (the four rear wheels) or in six-wheel drive. Six wheel drive capabilities facilitates existing in the water. Maximum speed on land is 40 miles an hour and its speed in water is about 6 knots.

In the early 60's the Stalwart was used as a British military transport across Eastern Europe in the event of a land war with the Warsaw Pact. Its sole purpose was to carry 5 tons of stores over very rough ground and it could traverse rivers and lakes using its internal Dowry water jet propulsion system. Because of its unique maneuverability on land and in the water, the military decided it would be very useful in its operations as an artillery ammunition vehicle. In the 1980's the military promoted a transition toward an all diesel fleet.

During this transition the Stalwart and similar Alvis vehicles with the Rolls Royce gasoline engine became somewhat outdated. Unfortunately, high tech advancements in helicopter design rendered this no nonsense vehicle prematurely obsolete. The gradual disposal of the Stalwarts in the 1980's and 1990 did achieve greater fuel standardization, but no equivalent off road amphibious cargo carrier has replaced them.