Although she is the sole credited writer on "Sunday, Bloody Sunday", several people have suggested that others were involved. Two writers,
David Sherwin and
Ken Levison, are given a non-specific acknowledgment in the end credits of the film, and Sherwin has several times said that he did a full rewrite on the script. When the film opened in London in 1971, the review in "The Times" newspaper mentioned this alleged contribution; there was an immediate retraction after a complaint by Penelope Gilliatt, who was always most insistent that she alone wrote the film. After her death, director
John Schlesinger was extremely vituperative about her, according to his biographer William Mann, who also claims there was extensive rewriting.