Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 148,439 pages of information and 233,876 images on early companies, their products and the people who designed and built them.
of Cricklewood Works, London, NW2
1929 S. Smith and Sons (Motor Accessories) formed an Aircraft Instruments Department.
1931 Smiths Aircraft Instruments, Ltd., of Great Portland Street, London.
1937 Manufacturers and suppliers of aircraft instruments and accessories. "Essex" Fire Extinguishers. "Frazer-Nash" Wing-Tip Flare Device. "Harley" Aircraft Landing Lamps. Sole Concessionaires of "Husun" Navigational Instruments. 
1939 See Aircraft Industry Suppliers
1944 Private company.
1961 Manufacturers of all types of meters and instruments for aircraft.