Sinclair Cambridge (type 4).
8 digits, red LED.
Has [C], [CE] (clear last entry), and [%] keys.
Batteries: This model takes only 2x AAA.
Main integrated circuit - General Instruments G-595, here date coded to the end of 1975.
50 mm x 111 mm x 28 mm (2 x 4.4 x 1.1).
Made in England.
Note the use of LED displays made by Bowmar, the pioneering U.S. calculator manufacturer.
When first introduced in summer 1973 the Cambridge cost £43.95 Sterling [about US$100].
In Summer 1977 the mail-order discount price had dropped to £8.95 Sterling [about $US15].