Lotus Mark III was a single-seater sports car built by Colin Chapman as a 750 Racer.
[1] In 1951, Chapman began to focus on a car for road racing, rather than trials, to compete in the 750 Motor Club formula, which used the Austin 7 as a basis.
[2] It led to a demand for copies (an improved Mark IIIB (registered as ONK 408) was built for Adam Currie, for instance, was the first Lotus to be sold to a customer and the first car to wear the Lotus badge), as well as copies of the earlier Mark I.
By the end of the racing season, it was apparent the Mark III was the best 750 Formula car in England.
[1] At this time, Chapman was still working full-time at British Aluminium, and creating cars at nights and racing them, with the help of enthusiastic volunteers, on the weekends, but it was clear from the performance of the Mark III, and the demand, there was an opportunity here.