On the eve of its release, Fifty Shades of Grey director Sam Taylor-Johnson has broken her silence on what it was like to work with the book’s author E L James. In an interview with Porter magazine, she admitted “it was difficult, I’m not going to lie.”

“We definitely fought, but they were creative fights and we would resolve them,” the 47 year old continued. “We would have proper on-set barneys, and I'm not confrontational, but it was about finding a way between the two of us, satisfying her vision of what she'd written as well as my need to visualize this person on screen, but, you know, we got there.”

Sam Taylor Johnson
Director Sam Taylor-Johnson has spoken of her frustration of 'Fifty Shades of Grey'

Taylor-Johnson had hinted at disagreements in previous interviews, but was constrained by ongoing professional courtesy and the need to deliver the project.

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The Hollywood Reporter has also broken the story that James overruled Taylor-Johnson when it came to a dispute on how to end the film. Universal extended an exceptional degree of control over the project to James, whose real name is Erika Leonard, when they bought the movie rights to the book for a reported $5 million back in 2012.

An insider on the project, who apparently sides with Taylor-Johnson, said: “It ended on a really smart note and Erika wouldn't allow it. It's just a bummer.” Another insider echoed those sentiments, saying that James “was given a lot of power and has used every opportunity to flex that power.”

Fifty Shades of Grey, which fans hope will be the first instalment in a trilogy, is set to open on February 12th – just ahead of Valentine’s Day weekend. It stars Jamie Dornan as Christian Grey and Dakota Johnson as Anastasia Steele.

More: ‘Fifty Shades of Grey’ star Jamie Dornan talks filming sex scenes – “there is nothing sexy” about it

Check out the trailer for Fifty Shades of Grey here.