It may be the great spymaster’s last mystery. Who will break four decades of silence to come forward as John le Carré’s “secret mistress and muse”?

A hitherto unknown author, writing under the pseudonym Suleika Dawson, is to publish a new intimate memoir of the spy novelist called The Secret Heart. It is billed by its publisher as a portrait of le Carré “by the woman he kept secret for almost half his life”.

Dawson first met le Carré in September 1982 and worked as a researcher and abridger for his audiobooks. Their affair started the following August and continued until the late summer of 1985; it resumed for six months in March 1999. Le Carré was married to his second wife, Jane, for the entirety of the affair.

In a plot worthy of one of the George Smiley novels, Dawson’s real name and age are unknown. The pseudonym is believed to be inspired by Zuleika Dobson, the title and main character of a 1911 satire by the essayist Max Beerbohm. Dobson is an attractive young woman at Oxford University with whom men fall in love at first sight. All of the male undergraduates commit suicide at the end of the novel because she does not return their affections.

Le Carré was no stranger to such intrigue. Born in 1931, his real name was David Cornwell, and while an Oxford student he worked covertly for MI5, spying on far-left groups. When his con man father, Ronnie, was made bankrupt in 1954, le Carré taught first at the prep school Millfield, then French and German at Eton before joining the security service. He moved to MI6, the foreign intelligence service, and wrote three novels under an alias before his spying career ended when the Soviet defector Kim Philby revealed the identity of British agents.

The author had three sons with his first wife, Alison Sharp, and another with his second wife, Jane, whom he married in 1972. His youngest son, Nick, writes novels under the name Nick Harkaway. Le Carré died aged 89 after a fall at home in Cornwall in December 2020. Jane, who was 82, died just two months later.

Fittingly for a former spy, le Carré had many secrets — and was a serial adulterer. Adam Sisman, author of John le Carré: The Biography, published in 2015, said that there was a “general knowledge within the family that their father’s personal life was not blameless”, but he tended to keep his extramarital adventures “pretty secret”. When Sisman first told le Carré he wished to write a biography, the author told him the two “problem areas” to write about in his life were his time as a spy and his affairs, “or what he called ‘my reckless personal life’ ”.

It is billed by its publisher as a portrait of le Carré “by the woman he kept secret for almost half his life.”

Most of his infidelities have largely remained hidden from public view, in part to spare the feelings of his family. Sisman said that he had “compromised” and shied away from revealing too much about his affairs because he felt “queasy” about hurting Jane. He did reveal, however, that when le Carré was married to Alison, he started a relationship with Susan Kennaway, the wife of his friend, novelist and screenwriter James Kennaway.

Sisman said that le Carré felt “guilty” about his indiscretions, but being an adulterer and a spy had “similarities that it doesn’t take a genius to identify”.

Sisman twice met Dawson, who is British, while he was researching his own book, in a style reminiscent of a rendezvous from le Carré’s novels. He was introduced to her via a literary agent friend and first met her in Ealing Broadway, west London. Dawson said that she would not tell him what she looked like in advance, and they used a rolled-up newspaper as a signal. When Sisman told le Carré he had met his former lover, “he groaned”.

A young le Carré with his first wife, Alison Sharp, and their three sons, on the Greek island of Spetses, 1964.

“She’s an attractive woman, intelligent, and I can see why David was attracted to her both physically and personally,” said Sisman. “She’s an interesting person.” There was also a “big age gap” between the pair.

As well as helping le Carré abridge his audiobooks, Dawson helped him with research for A Perfect Spy, which is seen as his most autobiographical novel, featuring an intelligence officer with a con man father. “She will reveal things not just about le Carré, but also his work. There are clues to his own personal life in his novels. The two are much more closely related than people imagine,” Sisman said. “The Spy Who Came in from the Cold is related to his first extramarital adventure … Out of that adventure, misery and angst came, that was the grit in the oyster that produced the pearl.”

Sisman added: “My perception of the women he got involved with was that they were interesting, intelligent women with interesting careers. They certainly weren’t bits of fluff: he liked women with whom he could have an equal relationship. I suppose that it is to his credit, even if the idea of infidelity is not.”

Joel Simons, publishing director for nonfiction at HarperCollins, said fans of the spymaster’s work will relish the new book. “You can absolutely draw the parallels between real life and fiction,” he said. “She was a secret part of his life … It will satisfy a lot of readers the way that le Carré constructs things.”

Dawson’s book will be published on October 27, which may overshadow the publication of A Private Spy, a new collection of the author’s letters spanning his childhood through the Cold War until his final years, which will be released two weeks beforehand.

Le Carré’s estate said: “We have no comment to make on the publication of this memoir but wish its author Suleika Dawson all the best.”

Liam Kelly is an arts-and-entertainment correspondent, covering everything from books and TV to film and theater for The Sunday Times of London