Jane Birkin and Serge Gainsbourg had a love story on screen before forming a legendary couple in the city. The story begins in 1968 when the director Pierre Grimblat, future producer of Navarro, begins the preparation of a film entitled Slogan. The screenplay tells of the passionate and tormented love of an advertising film director with a young English girl. He has already decided to entrust the male role to Serge Gainsbourg.

He was told one evening about a charming actress who had begun a promising career in London, a certain Jane Birkin. She comes to Paris to audition. She doesn’t speak a word of French, stammers and ends up bursting into tears. Touched by his sensitivity, Grimblat hired him immediately. She signs her contract the next day and meets Serge Gainsbourg, whom she has never heard of.

Filming takes place in Italy, with the exception of a few scenes in the Val d’Oise, between Daumont and Saint Brice sous forêt near Montmorency. In one of them, the couple, victim of a car accident, find themselves on board a Triumph TR3 A, towed by a tow truck. It was rented by the production to a mechanic in the area and then bought by one of his colleagues, Mario Letellier. His wife fell in love with this convertible and he decided to give it to her for her birthday.

Nelly Letellier, his daughter, inherited it after his death and continued to maintain it with care. “The day filming ended, Dad was invited to a buffet where he chatted at length with Gainsbourg and the current passed,” she recalls. So when it was time to say goodbye, Serge went to the vehicle and put his signature on the dashboard. “One day, you’ll see, it’ll be worth gold!” he whispered. However, he did not imagine, then, becoming a cult.

A privileged spectator of the shots, Mario Letellier then often told his relatives behind the scenes. Nelly remembers her words: “Jane did not speak a word of French, and did not understand the dialogues that she systematically learned by heart. Serge was particularly disagreeable with her, but she obviously didn’t blame him. She was very impressed with his charisma. She found him incredibly charming, and felt very small in front of him. She never imagined for a moment that she could, one day, represent an interest in his eyes. A few weeks later, after a series of one-on-one dinners in great Parisian restaurants, she settled down in the private mansion at 5, rue de Verneuil, now transformed into a museum. Finally, in 1968, Jane Birkin confessed to Mario Letellier her happiness and her pride in shooting a long shot in an English automobile. Nelly Letellier took, with regret, the decision to part with it. She wants to pass the baton to a collector of old cars, or even a fan of Gainsbourg. “It dates from 1962, but the bodywork is impeccable and it drives perfectly”. Like on the first day of filming, when Pierre Grimblat launched “Moteur”!