Mestel left Cambridge in 1966 after being appointed to the position of professor at the University of Manchester, but before taking up his appointment there he spent the academic year of 1966–7 as JFK Fellow at the Weizmann Institute, Israel. Returning to England, he spent six years as professor of applied mathematics in Manchester (1967–1973). The fourth and final stage of his career was as professor of astronomy at the University of Sussex, a position he took up in 1973 and held for nineteen years.