Los Angeles - The Danish Girl "took 15 years to make".
The new biographical drama film - which stars Oscar-winning actor Eddie Redmayne - is based on the 2000 novel of the same name by David Ebershoff and the film's director Tom Hooper has revealed how tough it's been to bring his ideas to fruition.
The film centres on the life of Lili Elbe, one of the first known recipients of sex reassignment surgery, and Tom said: "The story happened around 1931. The film, based on the book, took 15 years to make. I worked on it seven years.
"The information's always been there, but this saga of courage was marginalised. Although I kept pushing the idea, this project remained sidelined.
"Financing wasn't happening so it became difficult. They said the film was hard to cast. Today, with the transgender experience out in the open, the timing is now obvious."
Tom also explained why he was so determined to have Eddie play the leading role.
He told the New York Post newspaper: "I always wanted a lead role for him. Playing this first transgender woman, Lili, he makes you feel her emotion every step of the way."
Watch the trailer here: