Author Philip Pullman reveals the details of the sixth and final book in his series, the core of his dark material and the core of The Dust Book.

The Rose Realm will be published on October 23 and will follow his heroine's story until her 20s.

She was 11 years old when she was introduced to her best-selling and award-winning first book in 1995, in his dark material book, Northern Lights.

Pullman, 78, said he was "relaxed" to "eventually be alive and be able to see it be made into a book and published."

Rose Field refers to magnetic or gravitational field, mentioned in the opening chapter of the Northern Lights, when scholars at Lyra's Oxford College secretly discussed a mysterious phenomenon called Dust.

The author told BBC Radio 4's World: "In the last book, Lyra is about to discover what dust is, what the story means, and how the story happens."

The former Oxford English teacher said the story also involves the nature of imagination. “I have a little idea of ​​the imagination, and Lyra finds what she thinks of the imagination, so we’re talking about that, too.”

Pullman revealed that in addition to the world of dust and daemon, the book is also affected by real-life global events, including the rise of tech billionaires.

"I've already known over the past decade that the influence of money and the power of the billionaire class, the power of the technology industry and all this extractive stuff like oil and gas, have had a much deeper impact on the world than I thought," he said.

“I think more deeply about myself while thinking about this, seeing the way the story goes away and seeing the decisions Lyra has to face and endure.

“The world has changed dramatically. We are either at the end of a long-term American power, which could end like the end of any empire, chaotic, destructive, and then gradually come together in new forms. It would be fun if I was still alive to watch.

"But we can also look back at the resources of the internet and so on... We are in an era of hundreds of years of wisdom and millennia. It's interesting to see if we do that. I doubt most of us won't, but some of us may."

Rose Field has published the previous book in the Dust Collection series for six years.

Publisher Midas said the first two books of the trilogy have sold 49 million copies worldwide.

Pullman said he now turns his attention to the planned memoir, which is the title I forgot about before.

"I've been talking about writing memoirs for a while before I forget everything, and that's probably coming," he said.

“I was born in 1946 and I was a child of the British Empire and it still existed. And I saw a lot of changes, like everyone at my age.

"It's not something compelling, but I've seen a lot of things that I like, like, make me happy, make me excited in all kinds of ways. I want to remember these things and write them down because I think it's a pity if they're not celebrated and remembered."