Norrish was a prisoner in World War I and later commented, with sadness, that many of his contemporaries and potential competitors at Cambridge had not survived the War. Military records show that 2nd Lieutenant Norrish of the Royal Artillery went missing (captured) in 21.3.18. Norrish rejoined Emmanuel College as a Research Fellow in 1925 and later became the Head of the Physical Chemistry Department at the University of Cambridge, occupying the left part of the Lensfield Road building with the other (and separate) department of 'Chemistry' (which encompassed organic, theoretical and inorganic chemistry) led by (Lord) Alexander R. Todd being accessed by going right at the main entrance. Both departments had separate administrative, technical and academic personnel until they merged to form one chemistry department under John Meurig Thomas in the early 1980s. Norrish researched photochemistry using continuous light sources (including after the war, searchlights).