His father had planned the life of a diplomat for him, in which a Cambridge degree in Law and a Call to the Bar were prerequisites. Cooper, however, confounded these plans by enrolling as an actor at the Webber Douglas Academy of Dramatic Art in London. A contemporary, joining on the same morning was the actor Michael Denison who recalls their first meeting in his autobiography "Overture & Beginners". Cooper's studies were interrupted by the Second World War. Initially conscripted into the ranks, he was selected for training at the Royal Military College, Sandhurst, gained a commission and was subsequently despatched to the Far East in 1942. He served as an infantry officer in the West Yorkshire Regiment, spending three grueling years in the jungles of Burma fighting the Japanese, on occasion hand-to-hand.