R. and J. Dempster
of Gas Plant Works, Oldham Road, Manchester. Telephone: Collyhurst 2554. Telegraphic Address. "Scrubber, Manchester". (1937)
1893 Private company.
1914 Gas and chemical plant manufacturers. Specialities: all kinds of structural ironwork, coke oven and blast furnace recovery plant, gasworks installations, elevators and conveyors, condensers, exhausters, steam engines and pumps. Employees 632. 
1935 See R. and J. Dempster:1935 Review
1937 Listed Exhibitor - British Industries Fair. Manufacturers of all types of Gas and Chemical Plant for Gas and Coke Oven Works. Condensers, Washers, Extractors, Gasholders, Tanks, Benzole, Ammonia and Tar Plants. Steel Mains and Structural Ironwork. (Stand No Ca.503) 
1961 Constructional gas and chemical plant engineers, producing gasholders, gas works plant and chemical plant. 600 employees. 
1962 Entire share capital purchased by R. T. Newsham.
1967 Chairman and major shareholder Ronald Thomas Newsham, was put on trial accused of committing serious accounting fraud against the company.