The film's alternative title S.W.A.L.K. is a common British abbreviation for Sealed With A Loving Kiss, a phrase that lovers write on the envelope of love letters to each other.
Jack Wild was playing an 11-year-old, despite being 17 at the time of filming in the early summer of 1970.
Although the film was a box office disappointment in both the United States and Britain, it turned out to be an enormous hit in Japan as well as in some Latin American countries such as Argentina and Chile, and a modest hit in South Africa.
Alan Parker spent several months visiting schools in London and tape recording conversations with the children about their experiences and thoughts before writing the script. According to producer, David Puttnam, "...large chunks of the film were lifted directly from the children's ideas".
Renowned filmmakers such as Alejandro González Iñárritu and Wes Anderson are proclaimed fans of the film. Iñárritu stated that it was one of the first films that created a huge impact on him when he first saw it as a child.