From the 1967 British movie Smashing Time. This tone-deaf dolly bird hits swinging London with gal pal Brenda (Rita Tushingham) and uses 10,000 pounds she won in a TV show to buy her way into being into a pop singer with her single "I'm So Young." She hits the charts and makes the cover of the New Musical Express. Her album is It's Yvonne.
Played by Lynn Redgrave.