The citation states that "his work is characterised by elegant experiments, skilful analyses and insightful explanations of observed phenomena."

Professor Johnson is an Emeritus Professor of the University and has worked in the field of contact mechanics and tribology for forty years; he recently retired after more than thirty years on the staff of the Department. He is the author of Contact Mechanics (CUP, 1985) and was awarded the Tribology Gold medal in 1985 and the ASME Mayo D Hersey medal in 1991.

Three Royal Medals, known also as The Queen's Medals, are awarded annually by the Sovereign upon the recommendation of the Council, two for the most important contributions to the advancement of Natural Knowledge (one to each of the two great divisions) and the other for distinguished contributions in the applied sciences. These awards are for contributions made within the British Commonwealth. The three medals are silver gilt.