Speaking from his recently renovated home, Boyne says he wanted to write a psychological drama, with multiple narrators, that traverses times and locations – by decades and across continents – with a malevolent character as the protagonist.
He has succeeded masterfully, creating the ultra-ambitious but largely talentless Maurice Swift, who plays fast and loose with the lives of others while plotting, slowly and deliberately, his own. Maurice is so charming he gets away with evil repeatedly - until he doesn't by which time you're uncertain as to whether to feel relieved or dejected.
"I wanted him to be quite a malicious character but I felt all the way along that I wanted to soften him a little bit, that you want to see some reason behind his actions, but I like the idea of novels where when you finish, you are never entirely sure where you stand."
Which leads to discussion of Patricia Highsmith and The Talented Mr Ripley with Tom Ripley so desirous of getting ahead that nothing or nobody will prevent it. Boyne acknowledges Ripley played a "quite big" role in the ideas behind A Ladder to the Sky; he says it's a homage to Highsmith and Ripley but he doesn't think the stories are similar.
Can Boyne relate to Maurice's all-consuming ambition?
"When I was that age [we meet Maurice in his early 20s], I was desperate to become a writer and get published; it was the only thing I wanted to do and I can remember that unending desire," he says. "It's hard because there are only a few people who are able to make a fulltime career in writing, so you're constantly wondering, 'Am I going to be able to break in?'"
He says Maurice is loosely based on a young writer he met on the writers' festival circuit and describes as very ambitious, kicking off the initial impetus to write about what ends a person might do to obtain their goals.
The seven deadly sins – lust, gluttony, greed, sloth, wrath, envy and pride – are shot through the novel, the undoing of the mere mortals who populate the pages of A Ladder to the Sky. Pride, it seems, still comes before a fall.
Given the complexities of what Boyne set out to achieve, you might think he went into it with some sort of strategic plan but he worked the way he always likes to work and simply got on with it. He acknowledges scrapping 10,000 words or so in the final section and deciding to introduce, between the three main sections, two "interludes".
These serve as the literary equivalent of a palate cleanser; Boyne says they were important to move the story along and keep the narrative consistent. While there are three main narrators, he didn't want readers to feel they were looking at totally disparate stories.
A Ladder to the Sky has received almost – but not quite – universally positive reviews, so Boyne's happy with the response and already on to his next project. It's been three years since his last book for young readers, so he's been working on another of those. He has no preference for writing adults or children's book, saying he enjoys both and, by and large, his writing process is the same.
The Boy in Striped Pyjamas, Boyne's first novel for young readers, propelled him to fame when it won multiple awards and was made into a film. With books now translated into 50 languages, Boyne has become one of the most respected writers of his generation, so to what does he credit his success?
"I'm very much a story-teller who writes from the heart and I always try to tell a good story. I'm an emotional writer, not an intellectual or experimental one. I try to write books that I think I would enjoy with real characters and real stories."