The real-life story that this film depicts unfolded as Orson Welles was making his film F for Fake (1973) in which the real Clifford Irving appears. Because of Irving's new-found notoriety, Welles was obliged to add some additional footage to his film.
The story is based on the true-life Clifford Irving, an American writer best known for his "authorized autobiography" of Howard Hughes, which turned out to be a hoax.
Source author and the real life hoaxster of the title, Clifford Irving, passed away19th December 2017. He was 87.
The actual Clifford Irving was hired by the production as technical adviser to the picture. The character in the film is portrayed by actor Richard Gere.