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Speciality chemicals and previous metals company, of 73/81 Hatton Garden, London, EC1. Telephone: Holborn 6989-97. Cables: "Matthey, London" (1929)
Ditto Address and Telephone. (Head Office and Refineries). Telegraphic Address: "Matthey, Smith, London". (1937)
of 73-83 Hatton Garden, London, EC1. Ditto Telephone. Cables: "Matthey, London". (1947)
of Royston, Hertfordshire and Pennsylvania, USA.(1974)
of Southgate (1975)
of Farringdon Street, London EC4A (2012)
1817 Company founded. Percival Norton Johnson established a business as a gold assayer, in London.
1822 The offices moved to 79 Hatton Garden.
1832 Johnson took George Stokes into partnership and the business then became known as Johnson and Stokes.
1835 The partnership ended when George Stokes died.
1837 Johnson then took W. J. Cock into partnership and the company became known as Johnson and Cock.
1851 George Matthey joined the company which was then changed to Johnson and Matthey
1852 Johnson and Matthey was appointed Official Assayers and Refiners to the Bank of England. The company had branches in Birmingham and Sheffield to supply the jewellery and silverware and cutlery trade with raw materials and ancillary supplies, such as silver solder and flux, which it manufactured.
1861 Johnson, Matthey and Co were approved as refiners to the Bank of England.
1867 At the Paris Exhibition, Johnson Matthey were awarded two gold medals for their fine display of refined and fabricated platinum.
1874 The company produced the first standard metre and weights in iridium-platinum for the international Metric Commission.
1875 Johnson Matthey supplied leads for the first electric lamps.
1880 The company supplied equipment to fabricate precious metal sheet, wire and tune for jewellery and industrial applications.
1891 Public company. In April the firm became a limited company - Johnson, Matthey and Company Limited. The company was registered on 11 April, to acquire the business of assayers and refiners of the firm of the same name. 
1894 Antwerp Exhibition. Specimens of Platinum. 
1901 Preference shares were listed on the London Stock Exchange.
1919 Acquired Johnson, Matthey and Co Inc of USA; (and a Birmingham Branch?) and possibly at Hadyn Park Works, Hammersmith, as planning records show them there in 1948 and 1952
1921 A London branch was opened in Poland Street, W1.
1925 Vast platinum deposits were discovered in Rustenburg, Transvaal, South Africa.
1926 Company research devised a process for extracting and refining platinum group metals. Acquired Johnson and Sons, Assayers; Johnson and Sons, Smelting Works; JM Vienna.
1927 Company acquired a major interest in an American Platinum works (established 1822).
1928 Johnson, Matthey and Co patented the only workable process for extracting and refining of platinum group metals from the South African ores.
1929 British Industries Fair Advert as Manufacturer of Liquid Golds and Alloyed Golds. Also Bullion Dealers, Assayers, Refiners and Metallurgical Chemists. Melters and Assayers to the Bank of England, refiners, Sweep Grinders, Rollers and wire Drawers of Precious Metals. Chemical Compounds, Ceramic Products, Screws for Contacts, Wireless, Optical and Scientific work. (Jewellery Section - Stand Nos. J.39 and J.58) 
1937 British Industries Fair Advert for Precious Metals and other Special Products for the Electrical, Chemical and General Engineering, Industries. Platinum Laboratory Apparatus. Pure Silver Plant. Sil-Fos Brazing Alloy. Silver Solders. Electrical Contacts. Fine Wire and Strip. Silver Fuse Wires. Fusible Alloys. Fine Silver Anodes.(Engineering/Metals/Quarry, Roads and Mining/Transport Section - Stand No. Cb.312) 
1938 Research and Development laboratories were built in Wembley and some mechanical production operations were relocated from London.
1946 The company won exclusive contracts for the refining of British demonitised silver coinage.
1947 Listed Exhibitor - British Industries Fair. Assayers, Bullion Dealers, Refiners of Gold, silver and Platinum in all forms for Industrial, Jewellery and Dental Purposes. Rolled Gold. Ceramic Colours and Liquid Precious Metals. Manufacturing and Analytical Chemists. (Olympia, ground Floor, Stand No. E.1747) 
1948 Johnson, Matthey and Co acquired subsidiaries in Australia and New Zealand.
1950s Manufacturing operations were gradually relocated from Hatton Garden to Harlow, Wembley and Royston. New production and sales outlets established in Austria, Belgium, France, Holland, Italy, Spain and Sweden.
1957 the company began publishinga journal, "Platinum Metals Review".
1961 Refiners of gold, silver and metals of the platinum groups, manufacturers of precious metals, salts, sheet and components, ceramic, enamel and transfers. 5,000 employees. 
1964 Associated company Arora-Matthey formed in India.
1968 Two Queen's Awards to Industry for Export Achievement. 
1974 The world’s first catalysts to control vehicle pollution were produced at Johnson Matthey’s Royston plant.
1974 Opened two automotive catalyst production plants.
1975 Head Office moved from Hatton Garden to Southgate, North London. The Technology Centre moved from Wembley to Sonning Common.
1981 Became a Public Limited Company in July.
1983 Opened a gold refinery at Salt Lake City, USA. Commercialisation of platinum-based anticancer drugs.
1989 worldwide annual turnover of Johnson Matthey was £1.43 billion, with industrial plants in Evere (Belgium), Wayne (Pennsylvania) and Kogarah (Australia).
1993 Sold UK and Irish jewellery business. Opened a new technology centre in Japan and a diesel catalyst technical centre in Sweden. The Catalytic Systems Division won two Queen’s Awards for Environment Achievement and for Export
1998 Johnson Matthey bought Cookson's share of Cookson Matthey Ceramics, which was renamed Johnson Matthey’s Colours & Coatings Division. Johnson Matthey sold its Hatton Garden site. It opened an autocatalyst production facility in Argentina
1999 Sale of the Electronic Materials Division
2000 New autocatalyst manufacturing plant in India. MacRobert Award (its 2nd) for the Continuously Regenerating Trap system to control emissions from heavy diesel vehicles
2001 New autocatalyst plant in UK. Autocatalyst production facility in China opened. Fuel cell membrane electrode assembly manufacturing facility under construction at Swindon. Acquisition of Pharm-Eco Laboratories and Meconic plc
2002 Acquired Synetix catalyst business from ICI, Cascade Biochem and Avocado Research Ltd.
2004 Sale of Pigments and Dispersions business
2008 Johnson Matthey acquired Argillon, a business specialising in catalysts, for €214 million.
2010 October: Acquired InterCAT, a supplier of fluid catalytic cracking additives for the petroleum refining industry, for $56.2 million.
see Johnson Matthey