Overview
The UK's film ratings are decided by the British Board of Film Classification and have been since 1912. Previously, there were no agreed rating standards, and local councils imposed their own - often differing - conditions or restrictions. For cinema releases, the BBFC has no legal power (technically, films do not even have to be submitted for classification), as it falls to councils to decide who should be admitted to a certain film, but they generally apply the BBFC's certificates, effectively making them legally-binding. In exceptional cases, councils may impose their own conditions, either raising or lowering the minimum entry age from the certificate, banning a certified film outright, or setting their own minimum entry age for films that have never been submitted for BBFC certification, or which have been refused a certificate by the Board.
Prior to 1985, there were no legally-binding ratings on video releases. The Video Recordings Act 1984 introduced new legal powers to certify video releases independently from any existing cinema certificate, with the BBFC being required to rate every new video release (except those exempted from classification) to determine the minimum age of people to whom the recording can be supplied, whether by sale or rental.
The following list chronicles the BBFC's ratings system from its inception to the present. Note that what is allowed in a film has greatly changed over time. A film rated 'A' in 1912 would probably be rated 'PG' now.
In each section, italics indicates when a certificate has changed since the previous system.
Read more about this topic: History Of British Film Certificates