Cinematograph Films Act 1927 was a piece of British legislation that came into force in 1928. It was designed to try and halt the decline in the British film industry. British cinema screens were dominated by American imports. If a British cinema wanted to show the latest American block buster they also had to agree to show a number of other films as well. As these films had recouped their production cost in American they could be provided cheaply, making it difficult for British made films to compete. The quota was set at 5% fro exhibitors and 7.5% for distributors and this increased to 20% by 1938.
The outcome of the act is mixed. On one level it was a success as the proportion of British films being shown increased to 25% and many were popular with audiences. The down side is that there were many low budget quickly made films of variable quality (the so called "quota quickies") many of which were made by subsidiaries of the big American companies. As a consequence many independent British film companies went out of business
What the quota did do was enable the building of sound studio's in Britain and also provided the opportunity for British actors, directors and technical staff to learn their skills, which includes some well known names: Madeleine Carroll, Errol Flynn, Rex Harrison, David Lean, Vivien Leigh, Margaret Lockwood, Ida Lupino, James Mason, Ray Milland, John Mills, Anna Neagle, Michael Powell, Margaret Rutherford, Alastair Sim, Ann Todd, Googie Withers