After initial training was completed, a rehearsal was undertaken at Romney Marsh, England. Upon the arrival of the team in Gibraltar, the men were assigned employment to serve as cover for their presence. Cooper's cover was dual: physician at the Gibraltar dockyard and censor of soldier's letters. However, the officer in Gibraltar who assigned men to vessels was not privy to Operation Tracer and Cooper was nearly sent to sea. Training for the Tracer team occurred on a regular basis. Cooper resided at the Rock Hotel; he would go through its front entrance in the uniform of a surgeon-lieutenant of the Royal Naval Volunteer Reserve, and exit through the back in the attire of a sergeant of the British Army. From there, he went into a tunnel for training. Later, he relocated to an apartment, with the Chief of Police as his roommate. During their off-duty time, the team was allowed to go into Spain, and Cooper recalls meeting athlete and actor Buster Crabbe during his stay in Gibraltar. However, Operation Tracer was never activated and, in August 1943, once the tide of the war had turned, orders went out for the cave to be sealed.