Sir Clive Marles Sinclair (born 30 July 1940) is an English entrepreneur and inventor, most commonly known for his work in consumer electronics in the late 1970s and early 1980s.After spending several years as assistant editor of Practical Wireless and Instrument Practice, Sinclair founded Sinclair Radionics in 1961, where he produced the first slim-line electronic pocket calculator in 1972 (the Sinclair Executive).