After his Ph.D, he worked at University College, where became professor of applied mathematics in 1967, and fellow in 1991. In 1953, he became a Commonwealth Fund Fellow. He then spent two years in the United States, one at Cornell University, one at Princeton University. While at Princeton, he and John Wheeler worked on electromagnetism and gravity, resulting in the proposition of "thermal geons" in a paper published in Reviews of Modern Physics in 1957.
