At Imperial College, he rose through the ranks from assistant lecturer (1945) through lecturer (1947) and reader (1955) and finally the Foundation Chair of Plant Pathology in the University of London (1964). He was also the secondary advisor to the pioneering Ghanaian plant pathologist,
George C. Clerk during his PhD studies. In 1950, he was a Commonwealth Fund Fellow. Additionally, he was a Research Fellow at the Connecticut Agricultural Experimental Station in 1957. Among his other positions were the Director of the NATO Advanced Study Institute in the years 1970, 1975 and 1980. He was the Sir C. V. Raman Professor at the University of Madras in 1980. His work covered botanical microbial infection, plant disease control, especially of soil-borne biotrophic pathogens and relatively unknown plant diseases. He also wrote the
Phytotoxins in Plant Diseases (1972) and
Active defense mechanisms in plants (1982) ==Awards and honours==