Around 1850 William Elliott took his two sons, Frederick Henry and Charles Alfred into the business and began trading as William Elliott and Sons. At the Great Exhibition of 1851 the company was awarded a Bronze Medal. William died in 1853 and in his will he left his share in the partnership to provide his wife, Emma, with an annuity. Frederick and Charles obtained patents for improvements in drawing boards, barometers, and telescopes. The company prospered, its success attributed to Frederick's business ability. Before long the Company was producing most of the standard optical, surveying, navigational and "philosophical" instruments for home and overseas customers.

By 1854 his two sons were trading as Elliott Bros and in 1857 they took over the firm of Watkins Hill. The company worked willingly with academics and others to realize their inventions; instruments for the new applications of electricity were produced and became an important part of the firm's activity. Customers included J. C. Maxwell, Charles Wheatstone, Lord Rayleigh and other leading scientists. Products from these years include galvanometers and batteries.

In the late 19th century, Elliot Brothers put their energies at the service of incoming telegraphy and electrical supply, in the 20th century also in industrial automation, computing and aviation. The Elliott Brothers disappeared in 1988, having been absorbed into BAE Systems.