Fifty Shades of Grey’s Christian Grey has become one of the literary world’s most infamous characters.

So just where did author E.L. James get the inspiration for the man who enjoys kinky S&M sex in his red room of pain?

Certainly not from her husband said the man himself, Niall Leonard, who appeared on Lorraine Kelly’s show on Daybreak this week.

The author’s husband said this is the question he is most often asked now his wife’s erotic novels have become bestsellers so he’s keen to set the record straight.

“It’s a fantasy, it’s certainly not based on me,” he said.

“In fact perhaps being married to me helped her to fantasize about someone more interesting. You are talking about a chap with a 32 inch waist and helicopter pilot licence so it’s certainly not based on me.”

Fifty Shades of Grey’s Christian Grey has become one of the literary world's most infamous characters

Leonard Niall said he and his wife, whose real name is Erika Mitchell, are still “coming to terms” with the success of her books. Since being published last year, they have become worldwide bestsellers, smashing records for paperback sales and making Erika Mitchell a fortune.

He said the sales have been beyond their dreams given Erika Mitchell only wrote the novels “for fun”.

He said: “She wrote it for herself, all the best books are written for the person who writes them. It was her own story, her own dream. She put it down on paper for a few friends to read it and then wanted it published to have her name on it.

“It was doing ok last summer and then it got bigger and bigger and then exploded. We’re still coming to terms with it, it’s happened so quick we’re both still in shock.”

The books have been so popular the film rights have been snapped up. Who will be cast in the role of Christian remains hotly anticipated with Ryan Gosling the current favorite for the part. But Leonard Niall said he is currently none the wiser on who will be cast despite his wife being involved in the film project.

“Every actor in Hollywood wants the part but I don’t know if it’s been cast yet,” he said.

The couple, who live in Ealing, London, with their two sons are both writers and Leonard Naill has recently published his own novel, Crusher, which he describes as a modern contemporary thriller.

Leonard Niall already worked as a TV screenwriter but was inspired to become a novelist by his wife – before her books became bestsellers.

He said: “She had a really good time doing it. I saw she was enjoying it so much and she was writing the story she wanted to be told.

“I wanted to sit down and write my own story. She said <<why don’t you?>> so that’s when I did.”

Leonard Niall pointed out his novel is nothing like his wife’s although he said it does have some “naughty bits”.