In addition to serving as co-creator and co-writer on their TV series during the 1960s and early 1970s, Anderson's primary contribution was character development and costume design. She regularly directed the bi-weekly voice recording sessions, and provided the voices of many female and child characters, in particular Lady Penelope in Thunderbirds.
Anderson was born in Camberwell, London, England, on 27 March 1927. Her father, Sidney Thomas, was a champion boxer, and her mother, Beatrice (née Aberdeen), a dressmaker.
After graduating from the London School of Economics with a degree in sociology and political science, she became a social worker. She emigrated to the United States to live with her first husband, an American golfer. Whilst in America she worked as a journalist.
Anderson returned to the United Kingdom in 1955 with a daughter. She joined the newly founded and short-lived Polytechnic Films as an office assistant in 1957. There, she met Gerry Anderson, an editor and director. That year, when Anderson and Arthur Provis created AP Films following Polytechnic's collapse, she joined them on the board of directors of the new company, alongside their colleagues John Read and Reg Hill.
In 1957 the company was commissioned by writer Roberta Leigh to produce films based on her children's stories, including The Adventures of Twizzle and Torchy the Battery Boy. Sylvia Anderson worked on these projects as a production assistant. Sometime between 1959 and 1961 the couple married, and she developed a wider role in production duties.
The couple worked together as a team, co-writing and co-creating the first episode of a series then sharing the work according to their strengths. Gerry tended to specialise in special effects and hardware, and Sylvia in character, voices, costume, dialogue and plotlines.
In this way, Anderson contributed plot development and voice work for a series of half-hour shows including Supercar, Stingray and Fireball XL5. However, she felt the half-hour format was insufficient to fully develop characters and stories, and she persuaded the team's TV producer Lew Grade to extend their shows to a full hour.
In the early 1960s, the Andersons co-created the series Thunderbirds, and Anderson created the characters. She was aware that Grade intended to sell the show to American TV networks and wanted to make the show appealing to American audiences, hence she introduced the "British aristocrat" character of Lady Penelope, and the "Cockney chauffeur" of Parker.
Lady Penelope Creighton-Ward, an aristocratic fashionista who was an undercover agent, was to become one of her most popular characters; Anderson both created the character and provided her voice. AP Films puppet designer Mary Turner used Anderson as the template for the creation of the Lady Penelope puppets, a decision of which Anderson was not immediately aware. Interviewed by the Daily Mirror in 1968, Turner commented: "we wanted a glamorous blonde and [Anderson] was the obvious choice." In 1966 and 1968, Anderson produced two feature-length films based on the Thunderbirds story, Thunderbirds Are Go and Thunderbird 6.
The Andersons' creative partnership ended when their marriage broke down during the production of the first series of Space: 1999 in 1975. Gerry announced his intention to separate on the evening of the wrap party, following which Sylvia ceased her involvement with the company, which by this time had twice been renamed and was now called Group Three. In 1983 she published a novel titled Love and Hisses and in 1994 she reprised her voice role as Lady Penelope for an episode of Absolutely Fabulous. She worked as a London-based talent scout for HBO for 30 years.
Her autobiography, Yes M'Lady, was first published in 1991; in 2007, it was re-published as My FAB Years with new material to bring it up to date with the latest developments in her life, such as her role as a production consultant for the 2004 live-action film adaptation of Thunderbirds.
Of the film, Anderson commented, "I'm personally thrilled that the production team have paid us the great compliment of bringing to life our original concept for the big screen. If we had made it ourselves (and we have had over 30 years to do it!) we could not have improved on this new version. It is a great tribute to the original creative team who inspired the movie all those years ago. It was a personal thrill for me to see my characters come to life on the big screen." My FAB Years was re-released as a spoken CD, narrated by Anderson, in 2010.
In 2013, Anderson worked with her daughter Dee, a jazz singer, on a concept for a new TV series named The Last Station. They set up a crowdfunding campaign on Indiegogo for followers to contribute and be a part of the series.
Anderson was also known for her charity work, particularly in support of Breast Cancer Care and Barnardo's.
In 1966, Thunderbirds received the Royal Television Society Silver Medal.
In 2015, Anderson travelled to Italy to receive a Pulcinella Award in recognition of her career in television production.
Anderson married Jack Brooks in 1946 with whom she had a daughter, Dee. She re-married in 1952 to George Thamm, which also resulted in divorce. She re-married for a third time in 1960 to Gerry Anderson, with whom she had a son, Gerry Anderson Jr before divorcing in 1980.
On 15 March 2016 (twelve days before her 89th birthday), Anderson died, following a short illness.Thunderbirds Are Go (2015) – voice artist (as Great Aunt Sylvia)
Crossroads to Crime (1960) – production assistant, uncredited acting role
Thunderbirds Are Go (1966) – co-writer, co-producer, voice artist
Thunderbird 6 (1968) – co-writer, co-producer, voice artist
Doppelgänger (1969) a.k.a. Journey to the Far Side of the Sun (US title) – co-writer, co-producer
Thunderbirds (2004) – production consultant