The association of Harold Roxbee Cox with the Air Registration Board began in 1938 (the year following its formation) with his appointment as its first chief technical officer — a post to which he was eminently suited by virtue of his experience and already formidable reputation in a wide range of technical aspects of aviation. Interrupted by the war, his service to the ARB was renewed first as consultant and member of the board, later (as Sir Harold Roxbee Cox) as its vice chairman and finally (as Lord Kings Norton) as its chairman.