She appeared in the films History of the World, Part I (1981) and Superman III (1983), and from 1984 to 1985, she was cast in season 10 of the American comedy-sketch television show Saturday Night Live.

In the late 1980s, Stephenson co-founded the protest group Parents for Safe Food, which successfully campaigned for a UK ban on the possibly carcinogenic plant growth regulator Alar being sprayed on apples and pears for human consumption.

She has presented a psychology themed interview show called Shrink Rap (2007), and has written Head Case: Treat Yourself to Better Mental Health (2009) and Sex Life: How Our Sexual Encounters and Experiences Define Who We Are (2011).

[3] She concealed the incident but when her parents learnt of her infection, they expelled her from the family home; according to Stephenson: "I remember the feeling well, because I still experience it every time someone rejects me, even in some relatively small way".

[1] According to media scholar Leon Hunt, a scene in which Stephenson plays a nurse from the inside of whose blouse one of the leads retrieves a live hand-grenade epitomises the programme.

[18] Among Stephenson's first appearances in the UK was a live, on-stage role in The Comic Strip with leads Rik Mayall, Peter Richardson and Alexei Sayle at Raymond Revuebar in Soho.

[19] Stephenson gained prominence with her part in the UK sketch-comedy television show Not the Nine O'Clock News (1979–1982) alongside Rowan Atkinson, Mel Smith and Griff Rhys Jones.

[25] In one Not the Nine O'Clock News sketch that became famous,[26][27] Stephenson played a car-rental receptionist who, when asked by a customer if he can use an American Express card, she replies: "That will do nicely, sir, and would you like to rub my tits, too?

[33] Stephenson acted in Mel Brooks' comedy film History of the World, Part I (1981); she later said she found it a dull experience due the lack of influence she had over the production.

[34] In 1982, she starred in the West End production of Joseph Papp's version of The Pirates of Penzance; The Times critic Irving Wardle wrote Stephenson "reveals unsuspected coloratura powers as Mabel, but the part wastes her comic gift".

[38] The following year, Stephenson released a four-track double single; the tracks were written by Richard James Burgess and one featured Gary Kemp on guitar.

[21] In the opening sequence, Ambrosia is the foil for a series of sight gags that reference Lester's The Knack ...and How to Get It (1965);[44] the character also has a love scene with Superman at the top of the Statue of Liberty.

[47] Stephenson starred alongside John Gielgud and Robert Hays in Scandalous (1984), which Rob Cohen directed;[21][48] critic Ben McCann said the film is "notable only for wasting the talents of all concerned".

[16]: 713  The same year, Stephenson appeared in the television drama Lost Empires; The Daily Telegraph critic Charles Clover called her was one of the positives in a dull series.

[63] She presented Move Over Darling (1990), a series of five BBC television programmes about the role of women at work and at home; the show had an all-female editorial team with Janet Street-Porter as executive producer.

Robbie Hudson of The Sunday Times wrote that it was "insubstantial" and "syrupy",[71] while Kirkus Reviews felt that, like the earlier book, it contained "incisive revelations".

The journey was documented in a four-part series shown on Sky Television and in her book Murder or Mutiny: Mystery, piracy and adventure in the Spice Islands (2006).

[74] Shrink Rap, in which Stephenson conducted psychology-based interviews with celebrities including Salman Rushdie, Carrie Fisher and Robin Williams premiered on More4 in 2007.

[75] Her book Head Case: Treat Yourself to Better Mental Health was published that year,[76][77] and was followed by Sex Life: How Our Sexual Encounters and Experiences Define Who We Are in 2011.

[80] In 2009, she received an honorary degree from Robert Gordon University[81] in recognition of "her achievement in the field of human sexuality where she has made a marked, sustained and international contribution".

[83] Stephenson was a guest on the BBC Radio 3 programme Private Passions in 2010, where her music choices included pieces by Vincenzo Bellini, Erik Satie and Claude Debussy.

Lee Randall of The Scotsman described it as "compelling and emotion-churning",[85] and Jane Wheatley of The Sydney Morning Herald said there is plenty of "humour and vivid anecdote", and that "the real heft of this book and its leitmotif is Stephenson's childhood experience of being rejected by her parents; a legacy that dogs her life to this day".

[86] Stephenson formed a dance company with Brazilian lambazouk dancer Braz Dos Santos, and wrote and produced a dance-drama stage production called Brazouka.

[96] In 1989, she led a group of celebrity mothers who went to 10 Downing Street to hand in a petition calling for a ban on the use of daminozide that was addressed to Prime Minister Margaret Thatcher.

[34][104] In 2002, on the BBC Radio 4 programme Devout Sceptics, Stephenson told Bel Mooney through Buddhism, "I could at last feel I had begun life as a wonderful piece of creation, that a person doesn't have to struggle every day to overcome darkness and sin".