According to the opening credits, Dr. Roger Corder's (Herbert Lom's) professional qualifications are M.D. (Doctor of Medicine), and D.P.M. (Diploma in Psychological Medicine).
Dr. Roger Corder's consulting rooms were found at 162 Harley Street, Marylebone, London. He also worked at St. Damian's Hospital.
Dr. Hugh L. Freeman, on behalf of the National Association for Mental Health (now Mind), was medical adviser on the series.
Herbert Lom had spent a lot of his career playing villains until this series came along. Being cast in the leading role as a sympathetic character, proved to be a change of pace for the actor.