The company can trace its roots back to 1912, when United Automobile Services was founded in the town to run bus services. United began a coach building business at the Lowestoft site in 1920. In 1931 the East Anglian operations of United were split off into a new company, Eastern Counties Omnibus Company, and Eastern Counties inherited the coach works - now concentrating on building bus bodies with a workforce of over 600 people. In July 1936 the coach works were separated into a new company, Eastern Coach Works, which developed into the largest full time employer in Lowestoft.
In May 1940 the factory received orders from the Military authorities to cease production. It was thought that, following the outbreak of World War II, the east coast would be the first target for an invading German army, so all wheeled vehicles were moved away from the site, so that they did not fall into enemy hands. As a result of this, 950 staff were laid off. By 1947 though, production was back to pre war levels.
ECW was nationalised in 1947. For the next 18 years its business consisted mainly of building bus bodies, which were mounted on Bristol chassis, for state-owned bus operators. In 1965 the state-owned Transport Holding Company sold a 25% share in ECW to Leyland Motors, which enabled ECW to sell to the private sector. During the 1960s it was common to see a bare bus chassis being driven through town by a goggle wearing driver, delivering the chassis for a body.
In 1969 ECW became part of a 50/50 joint venture between the National Bus Company (successor to the Transport Holding Company) and British Leyland (successor to Leyland Motors). The joint venture came to an end in 1982, when British Leyland took complete control, and ECW closed in 1987. ECW was one of Lowestoft's largest employers with around 1200 staff at its peak.