Research : The British Board Of Film Classification

The BBFC has been examining content since 1912, and puts movies into classifications of mature content. For example; movies with a U rating can be seen by all audiences, but those with a 12, 15, or 18 rating are restricted to younger audiences for having graphic scenes of violence, discrimination, drugs, horror, nudity, or sexual themes. The specific guidelines for a 15-rated movie are that; characters taking drugs can be shown, but only if the substances are not easy accessible (like aerosols or solvents), nudity/strong language/ and sexual scenes (in minimal detail) can be shown, but gore is unlikely to be acceptable.

The main classifications are;
 U (Universal) - can be seen by all audiences
PG (Parental Guidance) - young children can watch, but parents can choose wether they find the content okay for them.
 12A - suitable for 12 years and over
 12 - suitable for 12 years and over
15 - suitable only for ages 15 and over
 18 - suitable only for people aged 18 and over
 R18 - adults working for licensed premises only