Shirley Conran, the author of Lace and Superwoman, has died aged 91, her son the designer Jasper Conran has announced.

The bestselling “queen of the bonkbuster” was also the founder of the Maths Anxiety Trust, a not-for-profit organisation that aims to help people who experience anxiety or fear when faced with maths problems. Last week Conran was awarded a damehood in her bed in Charing Cross hospital in London for her services to mathematics education.

Jasper Conran released the news of his mother’s death on his personal Instagram account. “Shirl girl has flown away, a lark ascending,” he wrote. “Thank you to all the wonderful doctors and nurses and thank you to all of you kind, dear people who sent her so many beautiful messages that meant so much to her.”

Born in London, Conran attended a finishing school in Switzerland before training as a sculptor and painter and working in textile design for several years. In 1968 she joined the Daily Mail, initially as a design consultant. She became women’s editor and launched Femail, the newspaper’s first dedicated women’s section.

As a journalist, Conran went on to work as the women’s editor of the Observer, and as a columnist for Vanity Fair. After being diagnosed with myalgic encephalomyelitis (ME) in her late 30s, she could no longer work full-time, and started writing books.

By 1983, Conran had written her first bestseller, Superwoman, a housework manual in which she told women life was too short to stuff a mushroom, its follow-up Forever Superwoman, about having young children, and Futures, a guide to the menopause. Though her plan was to next write a guide to sex for schoolgirls, while researching it she “got so bored I thought I might as well have a go at writing a novel”, she told Rachel Cooke in a 2012 Observer interview. Lace, her world-famous debut novel about four friends who meet a film star in a Manhattan hotel, is “really intensely researched sexual information dressed up as a novel”, Conran told Cooke.

Lace has sold more than 3m copies in 35 countries. In 1984, it was adapted into a TV miniseries in the US starring Bess Armstrong, Brooke Adams and Arielle Dombasle. “Lace is exuberantly, fabulously over-the-top,” wrote Sarah Hughes on the novel’s 30th anniversary in 2012. “Its heroines suffer no fools, take no prisoners and leave few bonkbuster cliches unused.”

Conran, whose other novels include Savages, The Revenge and Tiger Eyes, was an active campaigner alongside her writing. In 1998 she set up Mothers In Management, in an attempt to improve working conditions and flexibility for working mothers. In 2001 she founded the Work-Life Balance Trust, a charity that lobbied for flexible hours for workers, and in 2004 she was awarded an OBE for services to equal opportunities.

It was also in 2004 that Conran was inspired to start campaigning about maths, after she failed to find a good maths textbook for her goddaughter. Prior to the Maths Anxiety Trust, which she founded in 2018, she had already set up Maths Action, an organisation with the aim of improving maths performance in Britain, and published Money Stuff, a maths course that follows the GCSE syllabus.

Conran was particularly interested in helping girls and women access mathematics. “This notion that maths is a male subject persists to this day. How often have you heard a girl say: ‘I’m hopeless at maths’?” she wrote in the Daily Mail in 2022, suggesting that better understanding of numbers would help women find the same level of financial success as men.

“Never mind ‘life’s too short to stuff a mushroom’,” she wrote. “These days I say: ‘Life’s too short to be short of money.’”

Conran was married to the British designer Terence Conran from 1955 to 1962. She described him as the “love of [her] life” after he died in 2020. She married again twice, first to John Stephenson and then to Kevin O’Sullivan, both sales directors, but realised she was “happier living alone” in her late 40s. Conran is survived by her two sons from her first marriage, Jasper and Sebastian, a product designer.