The 1999 book Who Paid the Piper?, Frances Stonor Saunders’s exposé of CIA-funded cultural espionage during the cold war, “single-handedly established a new branch of sub-history”, according to the novelist Ian McEwan.

Translated into 17 languages, the book established Frances, then in her early 30s, as one of the most exciting nonfiction writers of her generation.

Through trawling declassified documents and countless interviews, Frances revealed how the CIA, under the guise of the Congress for Cultural Freedom, was behind thousands of books, magazines, exhibitions and concerts. She showed that many of the intellectual elite of the time – including George Orwell, Hannah Arendt and Jackson Pollock – had, knowingly or otherwise, become tools of the American secret service.

The book itself has had a long reach. The former prime minister Gordon Brown said it had inspired and intrigued him when he took office in 2007. More recently, it sparked the New Yorker writer Patrick Radden Keefe to create Wind of Change, the Guardian’s top podcast in 2020, which investigates the allegation that the Scorpions’ 90s power ballad of the same name was written by the CIA.

Frances, who has died aged 60 of a brain tumour, began her career in television. It was her work on a 1995 Channel 4 documentary series on the connection between abstract expressionism and the CIA that set her on the trail for Who Paid the Piper?

A determined sceptic, she had an instinct for sniffing out corruption or moral cowardice, and a magpie eye for a neglected snippet of history from which she could spin a much bigger story. An enduring fascination with secrets, memory, exile and borders (real and symbolic) runs throughout her books.

Who Paid the Piper?, her debut work, won the Royal Historical Society’s Gladstone book prize and was followed by Hawkwood, a gripping narrative history of a 14th-century mercenary, in 2004. The Woman Who Shot Mussolini, the story of a 50-year-old Anglo-Irish aristocrat, Violet Gibson, who failed to assassinate the Italian dictator in 1926, was published in 2010.

Her final book, The Suitcase, which grew from a series of essays for the London Review of Books, was her most personal, tracing her father’s journey as a boy escaping Romania to his descent into Alzheimer’s in his 50s. It won the PEN Ackerley prize for memoir in 2022.

Born in Windsor, Berkshire, Frances was the daughter of Julia Stonor, who belongs to one of England’s oldest aristocratic Catholic families, of Stonor Park, Oxfordshire, and Donald Saunders, born Donald Slomnicki in a small town near Bucharest. He came to Britain as a refugee after the second world war and became an investment banker.

Her parents divorced when Frances was eight, and she and her elder brother, Alexander, lived with their mother in west London. Theirs was a bohemian childhood, with a house always full of guests; Graham Greene was a family friend. Her half-brother, Hugo, was born after her father, who died in 1997, remarried.

Frances always said she was the “black sheep” at St Mary’s convent school in Ascot, but she was made head girl all the same. At Oxford University, where she studied English at St Anne’s College, she shared a flat with the novelist Zoë Heller and the Observer arts journalist Vanessa Thorpe.

Among her many friends, she was famous for being clever, following the tag from Muriel Spark’s The Prime of Miss Jean Brodie. After graduation in 1987, Frances lived in Rome, and stayed with Spark at her home in Tuscany, the author recognising a shared dark humour. This was followed by a stint as unofficial tour manager for the American singer Eartha Kitt, another family acquaintance.

Working as a freelance for C4, Frances realised that her first series, Hidden Hands: A Different History of Modernism, had the makings of a book. After the success of Who Paid the Piper?, she was hired as arts editor of the New Statesman. I met her there, when I became her deputy.

She took me out for a glass of champagne on my first day, smoked on the fire-escape and put a prestigious playwright firmly in his place. But she was at once too intellectually restless and rigorous to work for a weekly magazine for long. She left in 2005 to immerse herself in her books, with shorter bursts writing radio documentaries for the BBC.

There, she brought erudition and wit to subjects you might otherwise never have encountered, ranging from Homer’s Odysseus (2016) to Trump at Studio 54 (2017). She was the ideal presenter for Radio 3’s Meeting of Minds (2004-07), a series documenting the meetings of intellectuals across history.

She worked with the director Amir Amirani on the film We Are Many, about the anti-Iraq war protests of 2003 (on which we marched together). In 2018, she curated a photographic exhibition at Europe House in Westminster, for which she asked people what object they would choose if they were forced into exile. Shortly after the Russian invasion of Ukraine in 2022, she travelled to Kyiv, to put together a second exhibition.

Frances was made a member of the Royal Society of Literature in 2018. But for all the hours she spent at her desk she longed to be outdoors. She loved travelling and regarded Italy as a second home. In later years she spent many happy hours on her allotment. An intellectual in a dumbed-down world, she was in some ways out of her time. She refused to submit to the tyranny of digital culture and loathed the Smartphone she was given during her illness.

She was thrilled to know that Who Paid the Piper? is being reissued next month. A new foreword calls it a “masterpiece of investigative history”. Nearly 30 years after it was first published, the book’s warnings about the weaponisation of culture for political ends are all too timely.

Frances is survived by her mother and her brothers.

Frances Stonor Saunders, writer, broadcaster and documentary-maker, born 14 April 1966; died 31 August 2026