John le Carré is to open the door to his “secret world” for the first time in a memoir due to be published next autumn.

The spy novelist, who worked for MI5 and MI6 before he hit the bestseller charts with The Spy Who Came in from the Cold, will release The Pigeon Tunnel, subtitled “stories from my life”, in September 2016.

“Out of the secret world I once knew, I have tried to make a theatre for the larger worlds we inhabit,” he writes in the book. “First comes the imagining, then the search for reality. Then back to the imagining, and to the desk where I’m sitting now.”

Publisher Penguin Random House said The Pigeon Tunnel would be le Carré’s first work of non-fiction, adding that it “opens up” the “extraordinary writing life” of the author of novels from The Constant Gardener to Tinker Tailor Soldier Spy for the first time.

“It is an exhilarating journey into the worlds of his ‘secret sharers’ – the men and women who inspired some of his most enthralling novels – and a testament to the author’s unique and personal engagement with the last half-century,” said the publisher in a statement.

Although Le Carré, the pen name assumed by David Cornwell, has not written a memoir before, he has touched on his life in shorter pieces, and Adam Sisman is about to release a biography of the author. In his introduction to the 50th anniversary edition of The Spy Who Came in from the Cold, published two years ago, Le Carré wrote of how he penned the novel at the age of 30, when “as an intelligence officer in the guise of a junior diplomat at the British Embassy in Bonn, I was a secret to my colleagues, and much of the time to myself”.

His secret service employers approved the novel, he wrote, because they “seem to have concluded, rightly if reluctantly, that the book was sheer fiction from start to finish, uninformed by personal experience, and that accordingly it constituted no breach of security”.

The “world’s press”, however, disagreed, deciding that “the book was not merely authentic but some kind of revelatory Message from the Other Side”. “From the day my novel was published, I realised that now and forever more I was to be branded as the spy turned writer, rather than as a writer who, like scores of his kind, had done a stint in the secret world, and written about it,” wrote the novelist.

Le Carré’s agent Jonny Geller said that the author, who will be 84 next week and who will narrate the audiobook of The Pigeon Tunnel, had been asked “for years to write about his life, but he’s just been too busy writing fiction”.

“I believe he thought that now felt a good time,” said Geller. “What I found amazing about the book, reading it, was the energy of it. And it’s written with the same elegance he’s known for.”

Geller said the memoir would “unlock some of the mysteries of his books”, promising “insights into the creative mind, tales of adventures in the movie trade, encounters with the great and the not-so-good, intensely moving stories drawn from over 50 years of observing the world”, all told “in prose other writers would envy”.

Penguin Random House chief executive Tom Weldon said it was a “huge honour” to publish The Pigeon Tunnel, a book he described as “the story of our times as seen through the eyes of one of this country’s greatest novelists”.