The Reliant Regal was manufactured from 1952 to 1973 in both car and van form. As a three-wheeled vehicle having a lightweight (under 7 cwt, 355.6 kg) construction, under UK law it is considered a "tricycle", the same classification as a motorcycle and sidecar combination and as such can be driven on a full motorcycle licence, meaning you didn't have to pass your car driving test to drive one, just your motorbike test. They were also taxed as a motorcycle making them cheap to run, if a little expensive to buy, usually costing more than a BMC Mini.

In 1962, with the release of the Reliant Regal 3/25 (3 wheels, 25bhp), the van and estate versions were marketed as the Reliant Supervan. In 1969, the Regal 3/30 was introduced with a 700cc engine that produced 30 bhp and some updates to the front end treatment, this is the version modelled by Vanguards. It remained in production until 1973.