He remained at this university for his entire career apart from spending 1931 on sabbatical as Visiting Professor at Ohio State University in the USA. From 1924 until 1944 he was a special lecturer in spectroscopy in the Chemistry Department. He was then appointed to the Johnston Chair of Biochemistry in the Department of Biochemistry in 1944 until he retired in 1966. He continued to be active in science after his retirement.
His research focused initially on the application of spectroscopy to determining the structure of chemical compounds. From 1926 his work developed the use of absorption spectroscopy with biological molecules that absorbed light, allowing their concentration to be estimated in solutions. This technology, in collaboration with Ian Heilbrons interest in a therapy for rickets, led him to discover the vitamin A and several related compounds. His research group became focused on fat-soluble vitamins and was also among the first to identify ubiquinone and the polyprenol family of compounds. From 1955 until 1965 the focus of his groups research was isoprenoids.
During the Second World War he was involved in studies to understand the requirements of vitamin A by people that gave him a new interest in nutrition. After the war he organised meetings for industrial scientists around Merseyside about the use of spectroscopy
He was the chair of the government's Committee on Food Additives from 1963 to 1968.