The Cornish coast is a place Kate Morton returns to every so often in her fictions. It was the centrepiece of her second book, The Forgotten Garden, and it is the setting of her latest, The Lake House.

Yet it was only in June that Morton first tramped the coastal walks of this smugglers' outpost of English countryside. Each of Morton's five novels has been written in damp, tropical Brisbane. It couldn't make for sharper relief.

"I went [to Cornwall] in the proof-reading stage," says Morton. "I still had my hands on the novel and I was very much immersed in the text and the minutiae of the story, and it really did feel – I hate to use the word magic – but I did feel this strange and enchanted sense of having stepped into the pages of my own book.

''It was exactly as I imagined it. The seagulls were much bigger, that was different, but other than that it felt like something I had made up had come to life."

The Queenslander is speaking by phone from north London, where she and her musician husband, Davin Patterson, are on a six-month sabbatical, renting a Victorian brick townhouse a stone's throw from Hampstead Heath. They have three sons, aged 12, 7 and 2, all banished to the park this morning.

''I thought it wise with three little Australian boys who like to run, shout and wield toy swords," she says.

Even as a little girl, Morton says, England was always somewhere she roamed in her imagination. When she first picked up a notebook and decided she was going to try and write it wasn't even a conscious decision to set a novel there.

"That was just where the story took me,'' she says. "I was writing not so much to reflect or capture my own experience in words, I was always writing to entertain myself, to go somewhere, and that was the place I felt like going, perhaps because it's such a contrast to my real life.

''I sometimes wonder if living here will give me a much stronger drive to write about Australia, and bring Australia to life in my imaginative world."

Morton is one of Australia's most successful literary exports since Colleen McCullough. Her books have sold more than 10 million copies worldwide. She is big in Canada and has made it to the New York Times bestsellers list four times, with each of her previous titles.

And she has reached such commercial heights by romanticising an English Eden of manor houses and formal gardens reminiscent of Evelyn Waugh's Brideshead Revisited, Daphne de Maurier's Rebecca and Frances Hodgson Burnett's The Secret Garden, favourites of her childhood and teenage years.

In The Lake House, Morton uses the talismanic power of a deserted, masterless house to grant her heroine, Sadie Sparrow, passage back in time to investigate the cold case mystery of a toddler who disappears without a trace from an aristocratic country house on the night of a grand Midsummer Eve party.

The Lost Gardens of Heligan​, which were created by the Tremayne family, fell to ruin after World War I and were rediscovered and restored in the 1990s, were Morton's immediate inspiration for the atmospheric tale in which secrets reach through time to haunt the present.

While following the form of her previous four books, The Lake House is a much more overt attempt at a mystery story. Sparrow is her first detective character, a police constable on forced leave investigating two concurrent unsolved cases, one of which she is blamed for having botched.

"I really enjoyed the forward motion the detective figure gave the narrative," says Morton. "Sadie brings a certain expectation for readers, whereas usually I have to find a more circuitous way of involving my characters in the detection and solution of my plots."

Morton has adored mysteries since discovering The Famous Five and The Secret Seven series, and loves them still as an adult. They were doorways into a magical world where children could wield power over their destiny.

When Morton was a girl growing up on Tamborine Mountain, she would scramble up the avocado tree next to her bedroom window, and lose herself in the world of Enid Blyton.

"I can't go into a wooded grove now without remembering the whish, whish in The Enchanted Wood," says Morton. "It really got under my skin and became part of me very early in life."

In her writing, Morton says, she is constantly chasing the reverie of her childhood reading experiences, a pursuit she compares to Alice down the rabbit hole.

She is intrigued by the Oxford don Lewis Carroll and the Scottish playwright J.M. Barrie; not only by the tales they wove, but the complex personal relationships with the children that shared their lives.

Their beloved books Alice Through The Looking Glass and Peter and Wendy are about lost children, and all the characters in The Lake House are misfits. Morton plays with this riff, naming two characters Alice and Peter. Alice's mother, Eleanor, in turn is immortalised in the novel as the child in a Wonderland-esque book written by Alice's godfather.

The disappearance of a child was an idea Morton says she has long been meaning to write. The book's setting in 1933 refers to the kidnapping for ransom of the eldest son of aviator Charles Lindbergh, one of the most highly publicised crimes of the early 20th century.

But Morton says she was thinking more of the baffling disappearance in 1966 of the three Beaumont children from South Australia's Glenelg Beach when she came up with the idea of a child's disappearance.

Born in Adelaide, the eldest of three girls, a decade after the Beaumont siblings went missing, Morton says it's a haunting concept that children should seemingly disappear into thin air.

"It's been almost 50 years now, and we're still no closer to knowing what happened to them," she says. "My sister lives in Adelaide and I spend a lot of time there, and I can't walk along Glenelg beach without thinking of that hot Australia day and wondering what really happened.

''Theo's disappearance takes place under very different circumstances, and during a different decade in another country, but I did hope to replicate the sense of mythology that attaches to cases like that, and the way they can have a wider cultural resonance, even changing the way we behave as a society."

After leaving high school somewhat directionless, Morton studied English literature at the University of Queensland, earning first-class honours, then did her masters on the subject of Thomas Hardy, whose bleak studies of rural England might be regarded as the antithesis of her style of modern popular writing.

​It wasn't until her youngest sister asked her to read a romantic novel she had written that she considered writing professionally herself.

"At the same time a friend of mine had a book published, and this was the first living breathing author I had met,'' she remembers. ''I was still reading but I'd lost that sense of being lost completely within the world of a story and I wanted to recapture that."

The first two manuscripts were mysteries and went nowhere. "I'd looked at what was being published in store and tried to replicate that sort of genre," she says. "They were sent out and sent back to me with no interest at all. When I wrote The Shifting Fog I didn't think I was going to be published. I figured I would write what I love and put anything and everything into it."

Morton didn't look back. The Shifting Fog, a period drama of an aristocratic family in terminal decline, sold internationally to more than 10 countries as part of a two-book deal reported then to be worth a million dollars. She wrote it after her son Oliver was born. Morton was 29.

She started The Lake House when pregnant with Henry, her youngest, and drew on that dewy bond between mother and newborn in the descriptions of the infant Theo Edevane.

"Books are like time capsules,'' Morton says. "Everything you feel and experience and do plays a part and folds its way into the story, and the book would be slightly different if it was written in a different year. It used to trouble me because it was so changeable but now I really like that about books."

Morton says she has become better at hiding clues in plain sight, and knows how to write her way out of plot knots. Her obsession with place is one thing, however, she has been unable to write herself free of. Book number six is set in Cornwall, but having visited Morton is happy that it will be largely a work of imagination.

She says: "It's almost like you need to go, and be, and experience, and forget it all and remove yourself and let only the most pertinent and important and moving, the details that communicate the most and the best, rise to the surface or come through the filter. It's almost a bit too much to be surrounded by it all."

The Lake House is published by Allen & Unwin at $32.99. Buy now on Booktopia