Irish novelist John Banville's latest book looks at the taboo topic of underaged sex.

The Booker Prize-winning author's novel 'Ancient Light' centers on an affair between a 15-year-old boy and  a 35-year-old married woman. The story, which is set in a small town in Ireland during a summer in the 1950s, features explicit descriptions of sex between the two.

The story is told by the boy, now in his 60s, who looks back at the forbidden and illegal affair he had with his best friend's mother.

"Billy Gray was my best friend and I fell in love with his mother," the book starts.

When asked by the Irish Independent if he thought the book would be seen as controversial or obscene, Banville said, "Surely nothing nowadays can shock the reading public, which has been bombarded with all variety of obscenity since the Sixties. Not that I think my sad, loving couple are in any way obscene."

The acclaimed author said he did not see any reason to defend the book.

"If I defend the book it will mean I think it needs defending -- and I don't."

He also denied that the story was in any way based on his own experience.

"Ancient Light is a novel, not a memoir. When a novel contains what might be considered controversial material, people always say, 'Aha, this must be written from direct experience.'

"But it's not. The book is fiction. As a 15-year-old, I did not have an affair with a married woman -- more's the pity.

"There was no Mrs Gray, no Billy Gray, no boy (like the narrator) living in a small town with his widowed mother in a dingy boarding house in the 1950s. In fact, if there had been a Mrs Gray, I wouldn't have written about it.

"For a novelist, the imagination is all and everything is made up.

"Some readers find this hard to understand or accept. I remember, when my novel The Book Of Evidence (loosely based on the Malcolm Macarthur case) was published, I met a woman who worked in the prison service and said she was convinced I must have experience of jail, otherwise how could I have written about it so well in the opening pages of that book.

"I answered that not only did I have no experience of prison life, but I had never killed anyone either. The point being that the woman was giving me a larger compliment than she realised, since my fictional account of prison life convinced her that it must not be fiction."

From 'Ancient Light':

". . . I was adrift in a daze of tenderness and incredulous gratitude. A grown woman of my mother's age, but otherwise as unlike her as could be, had taken off her dress and unhooked her suspenders and stepped out of her drawers -- white, ample, sensible -- and with one stocking still up and the other sagging to the knee had lain down under me with her arms open . . . and even now had turned on her side again with a fluttery sigh of contentment and pressed her front to my back, her slip bunched around her waist . . . and was caressing my left temple with the pads of her fingers and crooning in my ear what seemed a softly salacious lullaby. How could I not think myself the town's, the nation's -- the world's! -- most favoured son and lavishly blest boy?"

'Ancient Light' by John Banville will be published on July 5 by Viking Penguin.