Manchester Oil Refinery Ltd, (sometimes known as M.O.R.) was established as a private company in 1936 by refugees Dr Georg Tugendhat and Dr Franz Kind, and was based in Trafford Park Manchester. The company began constructing a petroleum refinery to make lubricating and transformer oils, and started operations in 1938. Due to government restrictions enacted during the Second World War the refinery was shut down in 1941 but soon reopened when it was shown to be advantageous to refine products locally rather than rely on imports. In 1948 Manchester Oil Refinery acquired an interest in a Belgian refinery, increasing its stake over time. In 1949 the business became a public company with wholly-owned subsidiaries Puremor Ltd (formerly Manchester Transformer Oil Ltd), British Transformer Oil and Lubricants Ltd, Raven Oil Co Ltd, and Petromor Ltd. It had two further part-owned subsidiaries, Petroleum Inventions Ltd and Flexibox Ltd. By 1955 Manchester Oil Refinery had established a new subsidiary, Trafford Chemical Developments Ltd, and acquired the remaining shares in Petroleum Inventions Ltd. The company made a further acquisition in 1957, when Marine and Industrial Lubricants was purchased from Lambert Brothers. The business also invested in chemical distribution companies. In 1960 Manchester Oil Refinery was itself acquired by Lobitos Oilfields Ltd, adding to its refineries business. By 1963 the company was owned by the Burmah Oil Co.

Petrocarbon Limited was established in 1945 by Manchester Oil Refinery Limited (MOR) as a design and development company, and to raise money to allow Petrochemicals Limited to undertake the construction of the Carrington Refinery. In 1948 the group of companies was restructured and Petrocarbon became a subsidiary of Petrochemicals. This situation continued until 1953 when Petrochemicals separated itself from Manchester Oil Refinery Limited and also disposed of Petrocarbon, which remained a subsidiary of MOR. At this time the company also changed its name to Petrocarbon Development Limited. In 1957 the company was involved in the development of a polystyrene plant in Poland as well as constructing a plant of MOR and work with the Atomic Energy Research Establishment. By 1963 Petrocarbon Development Limited, along with its parent Manchester Oil Refinery Limited were part of the Burmah group.