Complex sentence: In 1970 he worked at the School of Environmental Sciences at the University of East Anglia, U.K., firstly as a Reader, then as Professor in 1974, and was Dean from 1977--1980, and again from 1993--1998.
Split into simpler sentences: In 1970 he moved to the School of Environmental Sciences at the University of East Anglia, becoming Professor there in 1974. He served as Dean from 1977--1980, and again from 1993--1998.