 Director Sidney Lumet saw the play "Equus" when it was first performed in London between 1973 and 1975, and also saw productions with Anthony Perkins and Richard Burton.Lumet found that Perkins' performance was excellent, but felt the stage productions failed to capture the conflict of the character Martin Dysart, which he believed was meant to represent writer Peter Shaffer's inner turmoil.Shaffer and Lumet spent more than one year preparing the screenplay before filming began.