John Gustav Jarmay was born on 31 December 1856, the son of Gustav de Jarmay of Hungary. He was educated in Hungary and England, where he trained as an industrial chemist. He became manager of Brunner, Mond & Co in 1880 and worked on the ammonia-soda process. He had over forty patents to his name, including some dealing with the manufacture of soda, soap and glass. He rose rapidly through the ranks and was appointed to the board of directors in 1889. He was largely reponsible for the technical progress of Brunner, Mond, as well as a number of other companies with which he was connected. At the outbreak of war in 1914 Jarmay led the industrial effort required to make sufficient explosives for the armed forces, and sat on a government committee dealing with high explosives. In 1918, on the recommendation of Lord Moulton, the minister of munitions, Gustav Jarmay was made a Knight Commander of the British Empire. In 1926 Brunner, Mond was absorbed into Imperial Chemical Industries, and Jarmay carried on his life in the chemical industry.
He married Charlotte Wyman on 2 June 1882 and they had one son, Istvan. Charlotte was very active with the Red Cross in Cheshire during the First World War and was made an OBE in 1919. They lived in Northwich, Cheshire during the most productive part of their lives, and having set up a home in Italy, returned to England at the outbreak of war in 1939. Charlotte died in September 1938 at Bulkeley Hall, near Malpas, Cheshire. Sir Gustav Jarmay retired to Hatfield, Hertfordshire, where he died on 22 August 1945. The son Istvan died in June 1946, and his only son John died in March 1948, aged only 36. What is known of his immediate family is presented here.
Ref: Matthew, H C. G. & Harrison, B. 2004. Oxford Dictionary of National Biography. Oxford University Press. Vol 29, Page 805.