In a nutshell
Golf-crazy Thomas made an art of analysing plant pigments and classifying the chemistry of dyes. He worked in the textile industry, including the dyes division of ICI.
Thomas suffered from a skin disease after working at the Nobel explosives factory in Scotland during the First World War, so he left to become Chief Chemist at the Solway Dyes Company. Here he was in his element as a researcher and soon got a name for his ability and disciplined work.
Partly in response to competition from German dye companies, Thomas coordinated his research teams and soon discovered new dyes that were accepted by the German companies and others. This was a time of prolific research and development.
Later he became Director of the dyes division of the famous company Imperial Chemical Industries (ICI).
For thousands of years, people have used dyes to change the colour of garments and to paint their faces for attracting or fighting others. These dyes were produced from plants and flowers, the process of production being handed down by example from generation to generation.
This went on until the 19th century when production became more systematic, but still not very scientific. John Thomas's rigorous analysis and classification moved on the scientific categorisation of pigments. He and his team were able to create several really important new dyes which would colour synthetic fibres like rayon.