“Gainsbourg and Bardot recorded a version of “Je T’Aime… Moi Non-Plus.” in a little booth at a studio in Paris, which resulted in some “heavy petting, according to engineer William Flageollet, during the recording. Stories of the pair’s steamy session and Bardot’s moans and breathiness on the recording only stirred more gossip in the news and angered her husband at the time German photographer Gunter Sachs.

Soon after, Bardot wrote a letter to Gainsbourg begging him not to release it. Gainsbourg obliged. At the time, Bardot was also set to star in Shalako with Sean Connery and didn’t want a deeper scandal brewing.

“The music is very pure,” Gainsbourg said in defense of his song. “For the first time in my life, I wrote a love song and it’s taken badly.” In 1986, Bardot permitted the release of her version of “Je T’Aime… Moi Non-Plus” with Gainsbourg.

Even though he initially shelved his recording with Bardot, Gainsbourg still wanted to release the song and asked everyone to be a duet partner, including Marianne Faithful, and French actresses Mireille Darc and Valérie Lagrange. “I don’t know how he got Jane [Birkin] to do it because she was such a lovely English upper-class schoolgirl,” said Faithfull in Sylvie Simmons’ 2002 book Serge Gainsbourg: A Fistful of Gitanes. “But of course, he would have got her to do it by f–king her brains out. And ‘Je t’aime…’ was perfect for Jane. She was born for it.”

After Gainsbourg met British actress Jane Birkin when both starred in the French romantic comedy Slogan in 1968 they were inseparable. They remained together for 12 years and shared a daughter singer, songwriter, and actress Charlotte Gainsbourg. Once filming was complete, Gainsbourg asked Birkin to sing “Je T’Aime” with him and she agreed, only because she didn’t want anyone else to record the sexy song with him.”