Under John's management, the Harlow laboratories became a company-wide centre of expertise in the use and interpretation of direct-reading X-Ray fluorescence spectroscopy to determine the quality of silver and copper alloys, as well as the purity of platinum, silver and gold samples as part of the company's staple business of precious metal assaying and certification.
The analytical techniques developed at Harlow during the 1960s and 1970s were applied across the Johnson Matthey group, including at its gold refining operation in Hatton Garden, in central London, its chemicals business at Brimsdown, near Enfield, and at its platinum refinery at Royston in Hertfordshire - the site where the first operational catalytic converters for the automotive industry were manufactured, and to where John relocated in 1985.
Johnson Matthey's brand and reputation were, and remain, synonymous with the accurate, precise and reliable determination of precious metal purity and the work of its Chief Analytical Chemist underwrote much of that integrity for more than three decades.
John Hookham's highly respected knowledge and experience in precious metal assaying techniques was sought by Goldsmiths Hall and the Royal Mint, amongst others, and by visiting delegations from several foreign governments. He was a member of the Royal Society of Chemistry throughout his career, achieving recognition for 60 years of membership in 2017.
John retired in 1990 and lived in Harlow until moving to Godalming in Surrey in 2019. His wife Irene died in 2005 and he is survived by their three children, five grandchildren and three great grandchildren.