Like many of the original 1973 London Cast and crew, Yasmin had appeared in a company of Hair, including the 1971 Norwegian cast. Pettigrew had been an assistant to Lauren Bacall, and had become friendly with Sue Blane and Tim Curry in the early '70s as well, which led directly to her employment at the Theatre Upstairs. Part of her early tasks involved searching for inexpensive used garb to use in the fledgling production, including Frank's first pair of shoes, which she glued the sequins onto. She became involved with costuming Rock Bottom for Annabel Leventon and Gaye Brown. When the play moved to Chelsea Classic, Pettigrew remained as costumer for the production.
Although she had no professional affiliation with The Rocky Horror Picture Show, Pettigrew visited the filming set several times. In 1981, she appeared in the audience in Shock Treatment along with Annabel and Gaye.