A.C. Cossor Ltd. was founded in 1859 by Alfred Charles Cossor in Clerkenwell, London. The factory was making scientific glassware. Cossor started with radio in the twenties, but only made factory-made radios since 1930. Before that, do-it-yourself kits where sold with names like "Melody Maker" and "King of the Air". Cossor was already an important valve maker. Before the Second World War, Cossor was the biggest radio producer in England, with a wide choice in types, although there was not much variety in design.

In the early 1930s the firm developed cathode ray tubes for television, the first television receivers, and the world's first radar receiver.

Cossor continued to trade for many years in Harlow Essex as part of the Raytheon group of companies. It got out of the consumer trade, but it did so by selling the right to use the name of "Cossor" for consumer products, not by selling the whole company. Radio's were produced until the sixties.