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of 23 Cross Street, Finsbury, EC2. (1922)
of 333 Hendon Way, Hendon, London, NW4. Telephone: Hendon 2070-1-2. Cables: "Caustic, London" (1929)
Ditto Address and Cables. Telephone: Hendon 8051-5. (1947)
1743 Established. Johnsons and Sons can trace its roots back to a goldsmith named Richard Wright who established his business in Maiden Lane in the City of London.
John Johnson became apprentice to Richard Wright and found himself in charge of the business soon after he had finished his apprenticeship. John Johnson had taken up the profession of Assayer and was the first private and independent Assayer in the City of London.
c.1839 Johnson and Sons began manufacturing chemical salts of silver and gold which were required for a photographic process recently invented by Fox Talbot - the negative-positive photographic process as we know it today. It was at this point, that Johnsons began their long association with photography.
World War I. Photography found strategic importance in the field of observation by the rapidly expanding Royal Flying Corps. Johnsons supplied the greater part of the requirements of photographic chemicals to RFC, the Royal Naval Air Service, and other Government departments using photography and were able to make supplies available to both the American and French fighting services.
1922 Listed Exhibitor - British Industries Fair. Metol-Johnsons, Amidol-Johnsons, Glycin, Acid Pyrogallic, Hydrokinone, Paramidophenol, Azol, etc.: and all Chemicals used for Photography and Cinematography. (Stand No. A.41) 
1927 The photographic chemical side of the business grew rapidly; the offices and warehouse moved from Finsbury to Hendon.
1929 Advert in British Industries Fair Catalogue as an Optical, Scientific and Photographic Exhibit. Manufacturers of fine Chemicals including Silver Nitrate, Gold Chloride, Amido-Johnsons, Metol-Johnsons, and all Photographic chemicals for Professionals, Process Engravers, Radiologists, Cinematographers, and Amateurs. Test Books of every description, etc. (Scientific Section - Stand Nos. K.68, O.24 O.43) 
1937 Manufacturing chemists. 
World War II. The company decided to concentrate solely on the photographic side of their business. The old-established business of Houghton-Butcher, of High Holborn, London, was destroyed by enemy action during in September 1940. In October, Ensign, the sales wing of H-B, was wound up and sale of the remaining stock of enlargers, epidiascopes and cine cameras was taken over by Johnson and Sons.
This was the beginning of a very long association for Johnsons of Hendon with both the manufacture and distribution of high grade photographic equipment. Over the next thirty years, Johnsons of Hendon produced developing tanks, enlargers, thermometers and darkroom accessories of all kinds and became distributors for most well-known names. Next door was the company's retail sales shop (directly connected), which used the name Houghtons - all that remained of the camera manufacturer that had been absorbed into the business many years earlier.
1947 British Industries Fair Advert as Manufacturers of Photographic Chemicals for Industrial, X-Ray, Commercial, Professional and amateur use. Silver Nitrate, Organic Silver Salts, Pure Litmus, Litmus and other Indicator Papers. Synthetic Dragons Blood and all other Process Engraving Chemicals. (Stand No. A.1061 - Olympia, Ground Floor, Stand No. A.1060) 
1948 The company became so closely identified with the district and its address that the company name was officially changed from Johnson and Sons, Manufacturing Chemists Ltd; to Johnsons of Hendon Limited. But Johnson and Sons had been using this business name in advertisements for at least two years previous to 1948, maybe since the end of WW2.
1970s Both shops closed in the early '70s and the managers retired. The site of Johnsons of Hendon is now occupied by the Brent Cross Shopping Centre, which was built in the late '70s.
1972 Johnsons of Hendon was acquired by the Hestair Company and underwent major restructuring and abandoned chemical production in 1974.