The long and complex history of this important firm begins around 1804 when William Elliott opened a shop in London. The firm became William Elliott & Sons in 1850, Elliott Bros. in 1853, and Elliott Bros. (London) Ltd. in 1916, and it was taken over by English Electric in 1966. Elliott Bros. showed their wares at all of the great nineteenth-century international exhibitions, and enjoyed appointments to the Admiralty, Ordnance, India Board, and Board of Trade. William Elliott had specialized in drawing instruments. Elliott Bros., however, offered a wide range of mathematical, optical, and philosophical apparatus, especially after having absorbed the firm of Watkins and Hill in the mid-1850s. Elliott Brothers became increasingly focused on electrical apparatus during the last quarter of the nineteenth century; they seem to have discontinued the manufacture of surveying instruments around World War I.
Ref: Gloria Clifton, “An Introduction to the History of Elliott Brothers up to 1900,” Bulletin of the Scientific Instrument Society 36 (1993): 2-7.
H. R. Bristow, “Elliott, Instrument Makers of London. Products, Customers and Development in the 19th Century,” Bulletin of the Scientific Instrument Society 36 (1993): 8-11.