most of his work continued to be about the electron theory of metals, he also looked at Dirac's hole theory, and co-wrote a paper with Bethe on the neutrino. The University of Manchester awarded him a D.Sc. degree. Moving back to Cambridge, he worked with David Shoenberg at the Mond Laboratory on superconductivity and liquid helium. To allow him to lecture, in accordance with its rules, St John's College, Cambridge, awarded him an ex officio M.A. degree. In 1936, Mark Oliphant was appointed the professor of physics at the University of Birmingham, and he approached Peierls about a new chair in applied mathematics that he was creating there. (Applied mathematics being what would today be called theoretical physics.) Peierls got the job despite competition from Harrie Massey and . The appointment at last gave Peierls a secure, permanent position. His students included Fred Hoyle and P. L. Kapur, a student from India. With Kapur he derived the dispersion formula for nuclear reactions originally given in perturbation theory by Gregory Breit and Eugene Wigner, but now included generalising conditions. This is now known as the Kapur–Peierls derivation. It is still used, but in 1947 Wigner and Leonard Eisenbud developed a more widely used alternative method. In 1938, Peierls paid visits to Copenhagen, where he collaborated with Bohr and George Placzek on a paper on what is now known as the Bohr–Peierls–Placzek relation. The Second World War broke out before it could be published; but drafts were circulated for comment, and it became one of the most cited unpublished papers of all time. Second World War Frisch–Peierls memorandum After the outbreak of the Second World War in September 1939, Peierls started working on nuclear weapons research with Otto Robert Frisch, a fellow refugee from Germany. Ironically, they were excluded from the work on radar at the University of Birmingham because it was considered too secret for scientists who were enemy aliens. Peierls was naturalised as a British subject on 27 March 1940. He was eager to participate in the fight against fascism and militarism, but the only organisation that would accept him was the Auxiliary Fire Service. He accepted an offer from the University of Toronto to send his two children to live with a family in Canada. In February and March 1940, Peierls and Frisch co-authored the Frisch–Peierls memorandum, which Peierls typed. This short paper was the first to establish that