Ow does film relate to the concept of  national identity ? Discuss in relation to British Realism

Say how does film in general relate to the concept of national identity. Use any british film s but Trainspotting would be a good starting point but dont focus all of the essay on it.

Hill, John: Sex, Class and Realism: British Cinema 1956-1963 (BFI, 1986)

Lay, S. British Social Realism: From Documentary to Brit Grit (Wallflower Press, 2002)

Friedman, Lester; British Cinema and Thatcherism (University College Press, 1993)

Murphy, Robert (ed) The British Cinema Book (BFI, 1997)

Use any other books you wish. Please use Harvard referencing.