We commonly consider films in terms of their genre - the set of characteristics that distinguish, say, a Western from a Comedy or a Thriller. We recognise genres by their narratives or their themes, but also by their iconography, characters and certain stylistic elements (for example, lighting, camera style). As audiences, we enjoy the repetition of the familiar, but also the injection of novelty and change to familiar forms.

British cinema, like other national cinemas, has favoured some genres over others - for obvious reasons, there have been few British Westerns - and has put its own distinctive spin on existing genres and invented new ones of its own. Some genres have evolved from the earliest days of film: many film Comedies have their roots in the slapstick or chase films of the silent period, while Britain's celebrated Documentary tradition has origins in early 'Actuality' films from the 1890s on, although it arguably came of age in the 1930s.

The character of British takes on genre often predate cinema - Social Realism (not exactly a genre, but such a dominant influence in Britain that it might be considered one) continues a tradition found in the literature of Charles Dickens and Thomas Hardy, among others. Genres also change over time - Brighton Rock (1949) and Lock, Stock and Two Smoking Barrels (1999) are both recognisably representatives of the Gangster genre, but the two films are worlds apart in style and content, reflecting changes in the medium and in Britain itself.

Equally significant is the way that filmmakers, working within or outside the mainstream, challenge, reject or actively oppose genre categories in order to give voice to ideas and positions frequently denied expression. Since the 1950s, Black and, later, Asian filmmakers have struggled to represent communities whose concerns have long been ignored by the mainstream, while Gay and Lesbian voices really began to be heard only in the last two decades. Similarly, Britain has a long history of artists using film to political - usually leftwing - ends.