Part of a season of documentaries about ethnicity in Britain. It is 40 years since Enoch Powell made his infamous Rivers of Blood speech. This film reassembles the surviving fragments of tape to recreate the whole speech. With interviews and a profile of Powell, we look beyond the incendiary language of the speech to try to understand why he predicted violence and separation. For related archive programmes visit http://www.bbc.co.uk/archive/white.