From wikipedia.org:
In 1983, Ullman succeeded as a singer on the legendary punk label Stiff Records, although her style was more comic romantic than punk. She had six songs in the British Top 100 in less than two years, including her first hit "Breakaway" (famous for her performance with a hairbrush as a microphone); the international hit "They Don't Know" (which got to ..2 and was written by label-mate Kirsty MacColl, who also sang backing vocals), and the Madness cover version "My Guy" (whose video featured the British politician Neil Kinnock, at the time the Leader of the Opposition).
Her songs were over-the-top evocations of 1960s and 1970s pop music with an 1980s edge, "somewhere between Minnie Mouse and The Supremes" as Britain's Melody Maker put it, or "retro before retro was cool", as a retrospective reviewer wrote in 2002. The video for "They Don't Know" featured a cameo from Paul McCartney; at the time Ullman was filming a minor role in McCartney's film Give My Regards To Broad Street. Her final hit was "Sunglasses" at the end of 1984.