Sylvia May Laura Syms was born on January 6, 1934, in London, England. She was educated at convent schools before receiving dramatic training at the Royal Academy of Dramatic Art. She made her stage debut in 1954 in a production of "The Apple Cart".
A repertory player, Syms was discovered for films by British star Anna Neagle and her director/husband Herbert Wilcox. She started her film career with "Teenage Bad Girl" (1956),playing Neagle's troubled daughter, followed by "No Time for Tears" (1957).
Syms' film list grew impressive in the late 1950s and early 1960s, working alongside notable actors such as John Mills, Anthony Quayle, Curd Jürgens, Orson Welles, Lilli Palmer, Yvonne Mitchell, Laurence Harvey, William Holden, and Dirk Bogarde. She played innocent love interests throughout her career, but never quite reached stardom.
Syms returned to the London theatre lights in 1964 to play the title role in "Peter Pan". She was nominated three times for British Film Academy Awards for her performances in "Woman in a Dressing Gown", "No Trees in the Street", and "The Tamarind Seed".
In the 1970s, Syms worked in TV series and played British prime minister Margaret Thatcher on stage and TV. She found herself immersed in character roles, offering support in films such as "Absolute Beginners", "Shirley Valentine", and "Shining Through".
The stage once again beckoned in the mid-to-late 1980s with touring performances in various plays. She portrayed the Queen and Margaret Thatcher in a production of "Ugly Rumours" and was among the cast in a musical presentation of "On the Town" in 2005.
Into the millennium, Syms continued to work, appearing in films such as "What a Girl Wants", "The Poseidon Adventure", "The Queen", "Is Anybody There?", "Booked Out", and "Together". She was also married once and divorced in the 1980s from Alvin Edney, and has a daughter and son who are also actors.