Modsports officially came into effect for the 1970 season as a development of the already well established and popular Marque production sports car format. The RAC set a uniform set of rules to keep the cars close to their road-legal version by only allowing the standard chassis , standard head and engine block and suspension-type.  These rules were all adopted by the clubs that ran Modsport championships or single events.

What it created was a fascinating mix of new and older cars often with little difference in  overall performance. Many older cars enjoyed a new lease of life after becoming slightly outdated in sports car racing such as the AC Cobra , Lotus Elan and Ginetta G4 which were allowed in for 1970. Modsports were also a showcase for the British kit-car industry and the likes of Ginetta , Clan and Davrian and featured during the 70s with works supported teams. By the end of the 80s the remaining cars were now racing along side modified saloons and the pure essence had disappeared .