The Obscene Publications Act (OPA) 1964 is a short piece of English legislation providing minor additional provisions in addition to the Obscene Publications Act 1959, which is the primary statute in this area.
The OPA 1964 was specifically designed to strengthen the law around obscenity, particularly regarding the production of obscene articles for sale and the materials used in the production of obscene articles.
References
Obscene Publications Act 1964 Wikipedia(Text) CC BY-SA