Costain Group plc is a British construction and engineering company headquartered in Maidenhead, England. It was established by Richard Costain and Richard Kneen in 1865, initially operating as builders in and around Lancashire. During the early 20th century, Costain expanded geographically, its main activities comprising housebuilding and mining. A separate London-based company was formed in 1923 by the Costain family and was floated on the London Stock Exchange ten years later. Shortly thereafter, Costain moved into civil engineering activities, such as its work on the Trans-Iranian Railway. During the Second World War, Costain helped build several Royal Ordnance Factories, airfields, and worked on the Mulberry harbour units. By the start of the 1970s, Costain was building around 1,000 houses per year. During this decade, it benefitted greatly from a construction boom in the Middle East; profits increased from little more than £1m per year to £47m within a decade. Wikipedia