In 1933 Edson won a Beit Memorial Medical Fellowship and spent two years at Cambridge University at the Sir William Dunn Institute of Biochemistry whose director was Frederick Gowland Hopkins. Edson became Hans Adolf Krebs's first PhD student. Edson spent from the Easter term of 1934 to the Easter term of 1936 in Cambridge (Emmanuel College), two instead of the usual three years of the PhD, and the term of the Fellowship. His mother's ill health required an early return to New Zealand. His thesis, "Studies in Intermediary Metabolism", gained him his PhD in December 1936.