The graphic novelist Posy Simmonds has won the Grand Prix at France’s Angoulême International Comics festival – the first time a British artist and author has been awarded the world’s most prestigious prize for lifetime achievement in comics.

Simmonds’s satirical observations on modern British society, interweaving detailed illustration with long literary texts, are held to have redefined the graphic novel genre.

She said of the award: “I was gobsmacked – époustouflée, as you would say in French … It’s extraordinary because if you’re writing or drawing, you work in a room on your own, and it’s then very extraordinary when the book, or your work, or you are given a lot of exposure.”

Simmonds, 78, whose work ran in the Guardian from the 1970s, is only the fourth woman to win the Grand Prix at the International Comics festival in Angoulême, which has been running for more than 50 years.

“I always think in a perfect world, the gender of a prize winner shouldn’t be remarkable,” Simmonds said. “But it’s an imperfect world and the comics and bande dessinée world has always been a masculine milieu, a bit of a boys’ club. But, bit by bit, especially over the last decade, women have infiltrated it, so I’m pleased to be one of them, of course.”

Simmonds began as a newspaper illustrator and started a weekly comic strip for the Guardian in the 1970s.

Her modern satire, Gemma Bovery, an updated reworking of the classic Madame Bovary by the French novelist Gustave Flaubert set among English expatriates in Normandy, was serialised by the Guardian in the 1990s.

Later, in 2005-2006, Simmonds’s Guardian series, Tamara Drewe, referenced Thomas Hardy’s Far From the Madding Crowd and explored the contrast between a country writers’ retreat and the reality of local rural life. Gemma Bovery and Tamara Drewe were both published as graphic novels and later turned into feature films.

In 2018, Simmonds’s graphic novel Cassandra Darke took as a starting point the character of Scrooge in A Christmas Carol, creating an antiheroine in the form of an art dealer living a Chelsea townhouse, entirely unbothered by other people’s opinions.

Simmonds has a big following in France, where she is known as “the queen of the British graphic novel” and has been described as a “subtle satirist” of modern times.

Her graphic work stands out not just for its piercing take on contemporary life, but also for the narrative and literary element in her texts, which have reworked female characters from 19th century literature. She has been described as an artist who “enjoys writing as much as drawing”.

Simmonds grew up in Berkshire, but her mother’s family had Huguenot roots in France. At 17, she studied French at the Sorbonne, and said France had influenced her.

She said: “When I arrived in Paris at 17, I couldn’t speak French. I could write it but couldn’t speak it. I addressed a gendarme as ‘tu’ and used ‘vous’ for dogs. But I picked it up quite quickly and of course I loved being in France. It was in the early 1960s, when things were still a bit sad in Britain, where the food wasn’t great, and suddenly being immersed in a place where you’d got real coffee and the food was terribly good, I had a wonderful time. So I think my connection to France dates from that. I had a total immersion, going to galleries and libraries and walking everywhere.”

She said that at first she had worried how Gemma Bovery, her reworking of Flaubert’s classic, would be received in France.

“I wanted to take the story of Madame Bovary but update it and it would be my story,” she said. “When it was published in French, I was rather frightened. I was worried it would be seen as lèse-majesté that I had appropriated this great French classic. But they really liked the book, which was wonderful.”

She said: “It was quite a different shape from French format and also I wrote a lot and I remember the French saying: ‘Gosh there’s a lot of text in your graphic novel’ – that was thought to make it a bit of a hybrid, not a classic form. But they liked it.”

The Angoulême Grand Prix comes as the Bibiliothèque Publique d’Information at the Pompidou centre in Paris is holding a major retrospective of Simmonds’ work, including unpublished, drawings, sketches and sketchbooks – from her press illustrations to her graphic novels and children’s books.

Simmonds, who is based in London, said she was working on a new project.

She said: “It’s early stages, so it’s in sketchbooks and I write little scenes … it’s on the stove, being cooked, but I may be some time.”

• Posy Simmonds: Dessiner la littérature is at the Bibliothèque Publique d’Information at the Centre Pompidou, Paris, until 1 April

• Cassandra Darke by Posy Simmonds (Vintage Publishing, £16.99). To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply.