 The Sinclair Sovereign was a high @-@ end calculator introduced by Clive Sinclair 's company Sinclair <unk> in 1976 . It was an attempt to escape from the unprofitable low end of the market , and one of the last calculators Sinclair produced . Made with a case of pressed steel that a variety of finishes , it cost between GB £ 30 and GB £ 60 at a time when other calculators could be purchased for under GB £ 5 . A number of factors meant that the Sovereign was not a commercial success , including the cost , high import <unk> on components , competition from cheaper calculators manufactured abroad , and the development of more power @-@ efficient designs using liquid @-@ crystal displays . Though it came with a five @-@ year guarantee , issues such as short battery life limited its usefulness . The company moved on to producing computers soon afterwards . 
