Without Jodie Foster, Martin Scorsese’s psychological thriller Taxi Driver wouldn’t be the masterpiece it revered as today. Robert De Niro rightly gets the plaudits for his mesmerising performance as ambivalent anti-hero Travis Bickle, but Foster plays off him in her supporting role like a seasoned pro.

The child actor was already five movies into her big-screen career and had worked with Taxi Driver director Scorsese on his previous film. But none of her earlier experiences could have prepared her for the role she was about to play. 12-year-old prostitute Iris Steensma is a hard-hitting part for an adult to act, let alone a star of Foster’s tender age.

As well as selling her body, pre-teen Iris is the main love interest of villainous, paedophilic pimp Sport, played by Harvey Keitel. In one scene, the two slow-dance to one of the movie’s musical themes before Sport kisses Iris. Parts of this scene had to be shot with Foster’s older sister as a stand-in for the actor, as using her for the kissing sequence at her age would have constituted child abuse.

Protagonist Bickle also makes it his mission to save Iris from her clients and the man enslaving her, resulting in the climactic shootout at the end of the film. The final scenes, whether real in the world of the movie or imagined inside Bickle’s own head, show him being celebrated as a hero, and thanked by Iris’ parents for rescuing her and returning her back to them.

Not only did Foster have to come to terms with the appalling sexual abuse her character was suffering, but needed to be in the room when acts of extreme violence were acted out, as the blood of Bickle and the pimps and paedophiles he was shooting splattered the walls. And she had to hold her own in acting terms, opposite two of the leading male actors of their generation.

Foster managed all of these things with aplomb while actually the same age as her character, Iris, was supposed to be at the time her scenes were shot. Foster was just 12 years old when she was cast in the movie, and shooting was completed within months of her casting due to budget constraints.

In light of the film’s adult themes, to ensure her safety, Foster was subject to a psychiatric evaluation before her casting was confirmed. She was accompanied by a social worker on set at all times, but, as she later told Conan O’Brien, had to contend with Scorsese “giggling uncontrollably” because of his discomfort directing such a young actress playing the type of role she was.

Nevertheless, she has happy memories of making the movie. To her, it was just “a great summer in New York where I kept going to the theatre”. It sounds like she was able to dissociate from her character better than many actors who are much older manage to do.