The extent of John le Carré’s meticulous research and attention to detail are among insights into his working methods that will be revealed when the master of spy thrillers’ private archive goes on display for the first time this autumn.

His classic cold war-era espionage novels have sold tens of millions of copies worldwide and inspired acclaimed films and television adaptations.

The Bodleian libraries at the University of Oxford have announced an exhibition starting in October, titled John le Carré: Tradecraft, drawing on thousands of papers in his vast private archive, which it holds.

Le Carré, whose real name was David Cornwell, wanted the archive to be placed with his alma mater, and after his death in 2020 aged 89 it was officially donated to the nation through the acceptance-in-lieu scheme, preventing its loss overseas.

Referring to his greatest fictional character, the self-effacing, quintessentially English spymaster George Smiley, le Carré once said: “Oxford was Smiley’s spiritual home, as it is mine.”

Exhibits seen for the first time will include his copious notes on his characters, as well as sketches in which, like a film director, he visualised those individuals in the margins of his manuscripts.

His annotated manuscripts will show the extent to which he revised his novels repeatedly. In a draft for Tinker Tailor Soldier Spy, he described Smiley as “small, podgy and at best middle-aged”, scribbling an insertion: “His legs were short, his gait anything but agile.”

Le Carré worked as a diplomat and a secret agent for MI5 and MI6 before his name was passed to the Russians by the traitor Kim Philby, who inspired the Soviet mole who infiltrated the highest ranks of the Secret Intelligence Service in Tinker Tailor Soldier Spy.

While le Carré elevated the spy novel to high art, creating a gritty antithesis to Ian Fleming’s glamorous James Bond, the exhibition will primarily portray him as a writer who had worked as a spy – as he saw himself – rather than as a spy who became a writer.

It will show how he gathered information, plotted stories and developed iconic characters such as Smiley and his counterpart Karla, the wily KGB spymaster. The archival papers reveal intricate timelines of plots.

The exhibition’s title plays on the term “tradecraft” that he used to describe the techniques of espionage, but which the curators said “might also be applied to his own skilled craft as a writer and social commentator”.

Private letters to be shown include a handwritten note that reveals his discomfort with public speculation about his spying career before it was actually confirmed. “Why do people want me to have views about spying? If I wrote about love, or cowboys, even sex, people would take it that this was my interest and therefore I made up stories about it,” he wrote.

There is also a letter in which the actor Alec Guinness doubted his suitability to play Smiley in the first television adaptation of Tinker Tailor Soldier Spy because he was “not really rotund and double-chinned”. Le Carré persuaded him to take on one of his most memorable roles.

The exhibition is co-curated by le Carré’s collaborator and longstanding friend Prof Federico Varese and Dr Jessica Douthwaite, of the Bodleian libraries, with the support of le Carré’s family.

Further reflecting le Carré’s rigorous approach to research, it will explore his close collaboration with intelligence operators, corporate whistleblowers and humanitarians and his dedication to exposing corruption, such as unethical practices in the pharmaceutical industry.

Varese, an Oxford professor of criminology whose books include The Russia Mafia, was among friends to whom le Carré would send early drafts of his novels. “He was very open to suggestions,” Varese said.

Having studied the archive’s contents, he said he had been surprised by the extent of le Carré’s research. “He was like an academic. He would go to the places he would be writing about and do fieldwork like an anthropologist or a sociologist. He would read extensively, interview people in the field, take notes – and then write it up as fiction. He would do it for all the novels, which is quite extraordinary.”

In staging the exhibition, he wants to “pay homage to a person I admire very much”.

• John le Carré: Tradecraft opens at the Weston library, Bodleian libraries, on 1 October, running until 6 April 2026. An accompanying book, Tradecraft: Writers on John le Carré, will be released by Bodleian Library Publishing.