<p>Ronald Wilfrid Gurney is one of the lesser-known research students of the Cavendish Laboratory in the mid 1920s. Gurney made significant contributions to the application of quantum mechanical tunnelling to problems related to alpha-decay from nuclei, to formation of images in photographic plates, the understanding of the origin of color-centres in salt crystals, the theory of semiconductors, and to the theory of electrochemistry and ionic solutions. He also made fundamental contributions to ballistics research. Gurney wrote a number of textbooks on fundamental and applied quantum mechanics in a distinctive intuitive and diagrammatic style which are still useful as educational resources. In addition to his scientific contributions, he travelled extensively, and before, during, and after World War II worked in the United States. During the cold war, he got entangled in the investigations of the Klaus Fuchs espionage affair and lost his security clearance and employment. During his work and travels, he interacted with many of the important figures of physics in the first half of the twentieth century. He died at the age of 54 in 1953 from a stroke. With the approach of the 100th year anniversary of quantum mechanics, it is timely to commemorate the life and contributions of this somewhat forgotten physicist.</p>