Pioneering author Doris Lessing, whose many works include feminist and science fiction, memoirs, thrillers and apocalyptic fables, has been awarded the Nobel Prize in Literature.

The 87-year-old writer of the proto-feminist novel The Golden Notebook is the second British writer, after Harold Pinter, to win the most prestigious prize in letters in the past three years.

Ms Lessing is the oldest-ever recipient and the 11th woman to win the prize in its 106-year history. She was described by the Nobel academy in Sweden as an "epicist of the female experience, who with scepticism, fire and visionary power has subjected a divided civilisation to scrutiny".

However, it was several hours yesterday before the London-based author knew she had won the prize - a lengthy trip to the shops meant she spent many hours oblivious to the honour.

When told of the award, she responded: "Oh Christ, I couldn't care less. This has been going on for 30 years.

"I've won all the prizes in Europe, every bloody one, so I'm delighted to win them all. It's a royal flush."

She recalled that, in the 1960s, "they sent one of their minions especially to tell me they didn't like me at the Nobel Prize and I would never get it".

Ms Lessing added: "So now they've decided they're going to give it to me. So why? I mean, why do they like me any better now than they did then? They can't give a Nobel to someone who's dead. I think they were probably thinking they had better give it to me now before I popped off."

Ms Lessing, whose work and thinking influenced a generation of writers, wins 10 million kroner (£765,000) for her life's work.

Jonathan Clowes, her agent, said: "It's very well deserved and we're absolutely delighted."

Although Ms Lessing's most influential work, 1962's The Golden Notebook, is still considered her most important, and a touchstone for the burgeoning feminist movement of that decade, the Swedish Academy's citation praised her entire, and prodigious, career.

Born Doris May Taylor to British parents in Persia, now Iran, she later moved to what is now Zimbabwe with her parents, a move which has influenced her writing throughout her career.

She worked as a nanny, telephonist, office worker, stenographer and journalist after her formal schooling ended at the age of 14, and had several short stories published before her first novel, The Grass Is Singing (1950), which examined the relationship between a white farmer's wife and her black servant.

Judges said her breakthrough novel The Golden Notebook "belongs to the handful of books that informed the 20th century view of the male-female relationship".

Jane Friedman, chief executive of Lessing's publisher HarperCollins, said the award was a complete surprise. "This is such wonderful news. This is extraordinary," she said.

Horace Engdahl, permanent secretary of the Swedish Academy, said Lessing's work had been of great importance to other writers and to the broader field of literature.

"She has been a subject for discussion by the academy for quite some time, and now the moment was right. Perhaps we could say that she is one of the most carefully considered decisions in the history of the Nobel Prize," he said.

"She has opened up a new area of experience that earlier had not been very accepted in literature. That has to do with, for instance, female sexuality."

Nicholas Pearson, Ms Lessing's editor, said: "Those early books changed the face of literature - the description of the inner lives of women."

In 1939, she married Frank Charles Wisdom, and the couple had a son, John, and daughter, Jean. They divorced in 1943. Two years later she married Gottfried Lessing, a German-Jewish immigrant she met at a Marxist group.

Ms Lessing became involved in the Southern Rhodesian Labour Party and when the couple divorced in 1949, she moved with their son Peter to London, while quickly establishing herself as a writer.

Between 1952 and 1956 Ms Lessing was a member of the British Communist Party and campaigned against nuclear weapons. She was banned from entering South Africa until 1995 because of her criticism of the regime. Following a brief visit to Southern Rhodesia in 1956, she was banned there for the same reason.

She was made a Companion of Honour in 1999.

Literary landmarks

  • The Grass is Singing (1950), her debut, which examines the relationship between a white farmer's wife and her black servant.
  • The semi-autobiographical Children of Violence series, largely set in Africa: Martha Quest (1952), A Proper Marriage (1954), A Ripple from the Storm (1958), Landlocked (1965) and The Four-Gated City (1969).
  • The Golden Notebook (1962). Her most famous book, the feminist movement saw it as a pioneering work.
  • Her landmark science fiction series, The Canopus in Argos, which ran in five books from 1979 to 1983.
  • The autobiographical works Under My Skin (1994) and Walking in the Shade (1997).
  • The Cleft, which was published this year: a haunting tale of a strange prehistoric culture.