She started singing in a band for £2 a night as a way of earning extra money while attending drama school. Her singing career began in Manchester, where under the name Karol Keyes (named after her management Keystone Promotions), she fronted “Karol Keyes and the Big Sound”, a band previously known as “The Fat Sound”. One of her first records was an Ike & Tina Turner number called "A Fool in Love" on Columbia. She left that band in June 1966. A year later, she joined Joan Littlewood’s drama school at the Theatre Royal Stratford East.
Her stage work includes A Man Most Likely To (1969, with George Cole), Pyjama Tops (1969), Decameron 73 (1973), playing Linda McCartney in John, Paul, George, Ringo and Bert (1974), Tom Stoppard's Dirty Linen (1976), Shut Your Eyes And Think Of England! (1978) and Funny Peculiar (1985).
Peters is known for her appearances in Hammer horror films of the 1970s such as Lust for a Vampire (1971) and Twins of Evil (1971). Other film credits include Man of Violence (1969), Freelance (1971), Not Tonight, Darling (1971), The Flesh and Blood Show (1972), Vampira (1974), Land of the Minotaur (1976), The Wildcats of St Trinian's (1980) and Pacific Banana (1981).
She was also active on television in series such as: Z-Cars, Public Eye, Coronation Street (playing series regular Lorna Shawcross in 1971), Doctor Who (in the serials Frontier in Space in 1973, and The Macra Terror in 1967), Target, The Professionals, and the Fawlty Towers episode The Psychiatrist playing Raylene Miles, an Australian tourist. Her last known television role was in an episode of The Bill in 1990. In 2005 she was interviewed for the documentary Fawlty Towers Revisited.
In 1972, she starred in the 13-part television series Go Girl, as a go-go Dancer who finds herself involved in action-oriented story lines. The series was beset by problems, which included the financiers backing out, the production running out of money, and the actors' union closing the production down. The series was never broadcast. The pilot episode only saw the light of day more than a decade after it was made, when it was released twice on UK video in the early 1980s - once under the title Give Me a Ring Sometime (which is actually just the pilot episode title) and on the second occasion as Passport to Murder.
