A number of factors meant that the Sovereign was not a commercial success, including the cost, high import levies on components, competition from cheaper calculators manufactured abroad, and the development of more power-efficient designs using liquid-crystal displays.

It had a Mostek MK50321N main integrated circuit and a small memory register, a LED display, and could perform a variety of a number of basic mathematical operations besides four-function arithmetic.

[2] Cheaper calculators with liquid-crystal displays instead of light-emitting diodes were becoming more popular, and had much longer battery lives of months or years.

[3][10] The loss of the calculator market was due in part to technological development leading to smaller and cheaper components, which put heavy pressure on profit margins.

[6] Sinclair also had some problems with the reliability of earlier calculators that had adversely affected its reputation, but the Sovereign was sold with a "full and unconditional" five year guarantee.

[11][12] The Sovereign came in satin chrome and gold-plated models, with leather pouches and fitted wooden cases.

[3][13] The Sovereign was unusual because the casing was made from pressed steel, which gave it a much higher quality feel compared to injection moulded plastic.

[19] As well as addition, subtraction, multiplication and division, it had reciprocal and square-root functions, and the ability to multiply by a fixed constant.