In 1955, Cullen was appointed as the first Professor of Electrical Engineering at the University of Sheffield. He then served as the Head of Department of Electronic and Electrical Engineering at
University College London where he held the
Pender Chair, from 1967 to 1980. In 1988 he published his book
Modern Radio Science and a biography of
Harold Barlow.
Awards and honours He was elected a
Fellow of the Royal Society (FRS) in 1977 The same year he was awarded the
Faraday Medal of the
Institute of Electrical Engineers. He also the same year delivered the
Clifford Paterson Lecture to the Royal Society on "Microwaves: the art and the science". ==Selected publications==