West Ham Gutta Percha Co
of West Ham, later Smithfield, London
1850 Charles Hancock, with the support of his family, established the West Ham Gutta Percha Co, on June 1, 1850 at Stratford in east London as a competitor to the Gutta Percha Co, with which he had been previously engaged.
1851 Advert mentions the patents of Charles Hancock and their speaking tubes at the 1851 Exhibition. Of West Ham, Stratford, Essex. 
Under the management of John Branscombe, it became a licensee of patents for gutta percha products as well as new machinery and products of Hancock’s design,
1852 Advert correcting malicious statements about the company. Signed by Charles Hancock and John Branscombe. 
1856 Expanded to works at 18 West Street, Smithfield.
1864 merged with S. W. Silver and Co, india rubber manufacturers.
Sources of Information
- The Times, Thursday, Mar 06, 1851
- The Times (london, England), Wednesday, May 05, 1852
- History of Hancock's companies: