Law debuted in films in a small role in the 1968 spy spoof "Otley" but until the 1990s, her feature roles were sparse. She was one of the fanatical fraulein's in "Hitler: The Last Ten Days" (1973), alongside Alec Guinness, and had a supporting role in the thriller "Tree of Hands/Innocent Victim" (1989). Her film career picked up when her then son-in-law Kenneth Branagh cast her as a dignified housekeeper in "Peter's Friends" and as the servant Ursula in his adaptation of "Much Ado About Nothing" (1993). In "Emma", Law had the wordless role of dotty old Mrs. Bates and subsequently essayed Sean Bean's mother in "Leo Tolstoy's 'Anna Karenina'" (1997). Her best screen role to date, however, came reprising her stage role as a feisty, somewhat meddling mother in "The Winter Guest" (1997). Appearing as the on-screen mother to real-life daughter Emma Thompson, Law delivered a touching performance and their off-screen relationship informed their portrayals.