 The ZX81 could be bought by mail order in kit form or pre @-@ assembled . In what was then a major innovation , it was the first cheap mass @-@ market home computer that could be bought from high street stores , led by W. H. Smith and soon many other retailers . The ZX81 marked the first time that computing in Britain became an activity for the general public , rather than the preserve of businesspeople and electronics hobbyists . It inspired the creation of a huge community of enthusiasts , some of whom founded their own businesses producing software and hardware for the ZX81 . Many went on to play a major role in the British computer industry in later years . The ZX81 's commercial success made Sinclair Research one of Britain 's leading computer manufacturers and earned a fortune and an eventual knighthood for the company 's founder , Sir Clive Sinclair . 
