"portnoy's Complaint is a 1972 comedy film written and directed by Ernest Lehman. His screenplay is based on the bestselling 1969 novel of the same name by Philip Roth.
The film focuses on the trials and tribulations of Alexander Portnoy, a Jewish man employed as the assistant commissioner of human opportunity for New York City. During a session with his psychoanalyst, he explores his childhood, his relationship with his overbearing mother, his sexual fantasies and desires, his problems with women, and his obsession with his own religion. Via flashbacks, we learn about his affairs with Bubbles Girardi, the daughter of a local hoodlum; Israeli Naomi; and gentile Mary Jane Reid, whose nickname "Monkey" reflects her remarkable agility at achieving a variety of sexual positions. Mary Jane seemingly is the girl of Portnoy's dreams, but as their relationship deepens and she begins to pressure him into giving her a ring, he shrinks from making a permanent commitment to her."
Although painted as a prototype for the central image of the British quad poster design, comparison to the final art suggests to me that Tom Chantrell might have tightened-up the detail on a print of the prototype art (rather than paint it all again!).