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Callenders Cable and Construction Co of Erith; of Falkirk, Scotland
also of Hamilton House, Victoria Embankment, London. (1937)
also of Norfolk House, Norfolk Street, London. (1949)
Callenders, originally an importer and refiner of bitumen for road construction, began manufacturing insulated cables in the 1880s at their Erith site on the Thames.
1870 William Ormiston Callender visited the asphalt deposits at Val de Travers, Switzerland; on his return, he set up Callender and Amos to act as agents for the Val de Travers Company of Neuchâtel to import asphalt for the many road-making schemes that were taking place in the City of London.
1877 William Callender obtained an interest in the import of bitumen from Trinidad for road-making and other waterproofing purposes. Took his two eldest sons, Thomas and William, into business as Callender and Sons, refiners of bitumen and for asphalt paving. Offices at 150 Leadenhall Street, London, with a small refinery at Millwall, where the bitumen was landed.
Thomas then arranged that all impurities be eliminated at source, which reduced costs.
The company won many overseas road-making contracts.
1880 Thomas saw the opera house in St Petersburg was lit by Jablochoff candles. To exploit the developing market for electric lighting, he decided to turn the business towards the production of large-capacity insulated cables.
1881 The elder William Callender patented vulcanized bitumen (which his son William had developed)
Tests on the production of insulated wire began at their new factory at Erith, Kent. The management of the Erith works became Thomas's responsibility.
1882 Callender's Bitumen Telegraph and Waterproof Company was formed to finance the development of vulcanized bitumen.
Early 1880s Thomas invented the Callender solid system where cables were laid in wooden troughs and embedded in bitumen.
1883 Cables were supplied for the electric lighting of the new law courts in the Strand and for the Covent Garden Opera House in 1883, as well as mains cables for the growing number of electricity supply companies.
1891 the firm introduced an underground electric haulage system at the Abercannaid colliery, Merthyr, and in the same year received its first tramways order, which was soon followed by the first electrified underground railway.
1896 Incorporated as a limited company and reconstructed as Callenders Cable and Construction Co. The company was registered on July 24th, to take over the business of Callenders Bitumen Telegraph and Waterproof Co. . Thomas Octavius Callender was managing director (a position he held until his death). The company was well placed to profit from the huge expansion in the uses of electricity.
By 1898 the number of contracts won had grown from 31 to 70; total sales over the same period had increased from £95,764 to £296,946.
1903 took over the Anchor Cable Co Ltd of Leigh, Lancashire. Mr. James Callender, in addition to his other duties, took over the Technical Management of Anchor Works, converting the factory from paper insulated- to rubber insulated-cables
1914 Manufacturers of cables of every description. Speciality: the "Solid System of Mains" and the insulation of cables by vulcanised bitumen. Employees 5,000. 
1916 Patent - Improvements in and/or connected with the Protection of Electric Supply or Distribution Systems in which Split or Parallel Conductors are Employed. 
1925 February 19th. Founding shareholder in Austin Electric Co
1925 Research project to investigate the failures of 33 kV cables
1934 Wood Lane Research Laboratories were opened by the Lord Rutherford of Nelson
1937 Cable makers and electrical engineers. "Anchor" Cables. "Callender" Cables. 
1939 See Aircraft Industry Suppliers
WWII: Developed method of dealing with magnetic mines using buoyant cable towed by 2 ships. Callenders (together with Glovers of Trafford Park, Manchester) manufactured the Pluto system (Pipelines under the Ocean) which was vital to supplying fuel to the Allied invasion force in 1944.