Vintage Sinclair

The Soverign was produced from 1976 and named to commemorate the Queen's Silver Jubilee. It was an attempt to move up in the market and Sinclair designer John Pemberton won a design council award for it.
It was small, slim, made from pressed steel and available in a range of finishes.There was black painted, satin chrome finish and silver or gold plated. A small number of solid gold models were also produced.
A chrome plated model cost about £30 in 1976.
It's downfall however was that it still used power-hungry LEDs when cheap LCD displays were becoming the norm whose batteries lasted for months. Soon Sinclair was selling them at a loss.

Display : 8 digit Red LED
Functions : +, -, *, /, %, memory, square root, square.
Batteries : 2 X watch batteries (2.5V)
Integrated circuit : Mostek MK50321N

Black painted model with case

Black painted model with higher quality case
Note the Ford logo embossed near the bottom

A black model with the Plessey logo embossed on the case

A gold plated version, costing £60 in 1976.

Chrome-plated or possibly silver-plated version.