Kestelman was born in London, the daughter of Dorothy Mary (née Creagh), a dress designer, and Morris Kestelman, an artist.[2][3] Her father was Jewish, from a family from Russia.[4] In 1994, she won a Laurence Olivier Theatre Award for her performance as Fraulein Schneider in Cabaret in the London revival of the show. She has performed with the Royal National Theatre and the Royal Shakespeare Company. In 1982, she performed in the play Macbeth, playing as Lady Macbeth. Kestelman joined the latter in 1968 but left in 1973 when she had her first role in a film as a scientist in Zardoz.