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Simms Motor Units of Percy Buildings, Greese St, Rathbone Place, London and of Oak Lane, East Finchley, London N2.
1913 Frederick Simms started another business, Simms Motor Units, initially as a sales and repair organisation for motor components, especially dynamos and magnetos. Manufacture was initially undertaken by others on behalf of the firm
WWI An important source of components for the company was the Simms Magneto Co of New Jersey, established by Simms in 1910.
1915 A subsidiary, the Standard Insulator Co, was established
The English workforce grew from twelve in 1913 to more than 300 by early 1919.
1920 October. Exhibited at the Commercial Motor Exhibition at Olympia with magneto equipment for commercial vehicles
1920 Simms established Simms Motor Units (1920) in extensive new premises in East Finchley, the Grange Works, where a variety of magnetos would be produced. The motor accessory department had been moved into the new works and the Wardour St premises given up. The magneto repair department was moved from 46-48 Foley St to 37 Percy St, London W. Had established a network of agents in UK and abroad, including handling exports from the American Simms Magneto Co
1920 The Kilburn works were virtually destroyed by fire.
1926 Substantial business in supplying magnetos and electric service for every kind of vehicle, in UK and abroad; the number of customers was about 11,500, about double that of 5 years previously. The company was renamed Simms Motor Units Ltd. The East Finchley works was reopened in the summer; half was occupied by Standard Insulator Co
1928 Simms Motor Units acquired the 75 percent of Standard Insulator that it didn't already own. Standard Insulator made vulcanite components for the Simms magnetos; it also sold enamelled wire, wireless components and other electrical items to which it had sole rights in the UK.
1930 the company began to move in new directions to match changing automotive technology, particularly the change from magnetos to dynamos; this resulted in the company making losses for some years.
1930 The works at Percy Buildings were moved to the factory at East Finchley
1935 Frederick Simms resigned from Simms Motor Units.
1938 Sales of diesel equipment had begun.
1939 Sales of aircraft magnetos began.
1939 See Aircraft Industry Suppliers
1944 Producing Uniflow injection pumps for diesel engines.
1944 Advert for Fuel Injection Equipment.
1956 Acquired Hadrill and Horstmann of London, makers of counterpoised adjustable lamps, Clearex Products Ltd, R. F. Landon and Partners which manufactured Kingsway burners and other oil-fired equipment. Formed Simplus Products to exploit various domestic products. Continuing its planned diversification, the company acquired Industrial Fan and Heater Co of Birmingham.. Acquired one-third of the shares in Aircraft Steel Structures Ltd.
1957 Simms Motor Units took over Motor and Electronics Corporation; the company name was changed to Simms Motor and Electronics Corporation; as a result Simms Motor Units became a private, holding company.
1961 Manufacturers of diesel fuel injection, electrical and other equipment for commercial vehicles and marine and industrial engines. 1,800 employees. 
1963 Motor Show exhibitor. Fuel injection systems. 
Manufacturing in East Finchley was steadily run down and the factory closed in 1991 to be redeveloped for housing. It is commemorated by Simms Gardens and Lucas Gardens.