After the war, he returns to working on the synthesis of sterols. In 1946, he joins the National Institute for Medical Research, first at Hampstead and then at Mill Hill, continuing the collaboration with Robinson. He identifies the structure of cholesterol with George Popjàk, by means of radioactive tracers. He also determines which cluster of hydrogen atoms in a substrate is replaced by an enzyme to effect a given change in the substrate, allowing him to detail the biosynthesis of cholesterol.

He completes a year of post-graduate research.

in 1975, Cornforth takes up a position of Royal Society Research Professor at the University of Sussex. He remains active in research until his death.

He dies on December 8, 2013.

John Warcup Cornforth is born on September 7, 1917, in Sydney (Australia), as the second of four children.

He enters the University of Sydney in 1934 to study organic chemistry. Though by that time unable to hear any lecture, he is attracted by laboratory work in organic chemistry (which he had done in an improvised laboratory at home since the age of 14) and by the availability of the original chemical literature. In 1937 he graduates with first-class honours and a University medal. 

In 1962, Cornforth and Popják leave the service of the Medical Research Council and become co-directors of the Milstead Laboratory of Chemical Enzymology set up by Shell Research Ltd. 

In 1939, he wins a Science Research Scholarship to work at Oxford with Robert Robinson (who would win the 1947 Nobel Prize in chemistry). A second scholarship is awarded to Rita Harradence, an organic chemist from Sydney. Their doctoral work is on steroid synthesis; in 1941, both graduate with a D. Phil. In Organic Chemistry.

John Cornforth shares the 1975 Nobel Prize in Chemistry with Vladimir Prelog for his work on the stereochemistry of enzyme-catalyzed reactions, especially the biosynthesis of cholesterol.

He marries Rita Harradence in 1941. The couple has three children and two grandchildren. Throughout his scientific career, his wife has been his most constant collaborator, making major contributions to the work and easing the difficulties of communication that accompany deafness. 

After his arrival at Oxford and during World War II, Cornforth works on penicillin, which was the major chemical project in Robinson's laboratory during the war, and he makes contributions particularly in purifying and concentrating it. He contributes to the authoring of  “The Chemistry of Penicillin” (Princeton University Press, 1949).

At an age of about ten years, the first signs of deafness (from otosclerosis) become noticeable. The total loss of hearing lasts more than a decade, so he can still attend Sydney Boys' High School. A young teacher influences him in the choice to pursue chemistry, since this seems a career where deafness might not be an insuperable handicap. He graduates in 1933.