Gillian was cast in the lead for the British classic "Beat Girl" released in 1960 at age 15 and recorded her first EP "Allo Brigitte? Ne coupez pas!” with Henri Salvador the same year. She released many more records, among them major hits like “Zou Bisou Bisou” which was chosen for the premier of the fifth season of the award winning American TV series "Mad Men" in 2012.
In 1961 Gillian went on tour with French singer Johnny Hallyday. Later on, in 1965, she would sign to the AZ record label run by the radio station Europe 1. In 1967 she played a role in Antonioni’s awarded, cinematic art film“Blow up” which won the Grand Prix at Cannes Film Festival.
Other film appearances followed, including a cameo in Stanley Kubrick’s A Clockwork Orange (1971). One year later, Gillian decided to stop acting and moved to New York to work as a successful book and magazine illustrator.
In 2012 Gillian met the producer Peter Vettese while he was recording with Zucchero and they started recording her album, “Lili.”