McGlashan was to spend the rest of the war as a prisoner-of-war in a series of five prison camps, including Stalag Luft IV, where he helped to set up and run the RAF School for Prisoners of War. This offered PoWs lectures on 34 subjects from Latin to hotel management. Although many of them went on to pass exams, McGlashan believed the true value of the courses lay in preserving morale in the camp. He also taught bridge.