He was cast as Thomas Becket in T. S. Eliot's "Murder in the Cathedral" in Robert Helpmann's production at The Old Vic theatre in 1952 but, although his return to stage was well received, his illness forced him to withdraw during the run. For the same reason, he dropped out of the film "Hobson's Choice" (1954). Scheduled to play Willy Mossop, he was replaced by John Mills. Author David Shipman speculates that Donat's asthma may have been psychosomatic: "His tragedy was that the promise of his early years was never fulfilled and that he was haunted by agonies of doubt and disappointment (which probably were the cause of his chronic asthma)." David Thomson also suggested this explanation, and Donat himself thought that his illness had a 90% basis in his psychology. In a 1980 interview with Barry Norman, his first wife, Ella Annesley Voysey (by then known as Ella Hall), said that Donat had an asthma attack as a psychosomatic response to the birth of their daughter. According to her: "Robert was full of fear."