A Forbidden Orange

Spain, 1970s. A Clockwork Orange, a film considered by critics and audiences as one of the best works in the history of cinema, directed by Stanley Kubrick and released in 1971, was banned by the strict Franco government. However, the film was finally premiered, without going through censorship, during the 20th edition of the Seminci, the Valladolid Film Festival, on April 24, 1975. How was this possible?