Operating under the name M. Cooper (Overalls) Ltd, from premises on Middlesex Street (aka Petitcoat Lane) in London's East End and centre of the garment industry/rag trade, they began production of workwear, having identified a market for it in South Africa.

[3] The outbreak of the Second World War in 1939 led Morris Cooper to split the business into two: one arm continued making workwear, while the other concentrated on producing military uniforms, battle fatigues and flight overalls.

He set about modernising the company and building on its wartime success, switching focus to casual wear and denim production, and taking advantage of the introduction of clothes rationing to increase competitiveness.

[6] Lee Cooper jeans were adopted by the youth counterculture of the 1950s and 1960s and Harold capitalised on this association by sponsoring a Rolling Stones tour and working with Serge Gainsbourg and Jane Birkin.

The company caused a degree of moral outrage in 1953 by introducing the zip-front to women's jeans[7] and commissioned a series of bold publicity campaigns, some of them incorporating fictitious designers such as the Italian 'Alfredo Angelous' in order to appeal to subcultures such as the Mods, who favoured continental style.