This week, at a special conference at Wembley, the Labour Party will decide how to choose its leader. Whatever it decides, the conference will mark a crucial stage in the party's history. Will the conference resolve the struggle between Right and Lef... (more)t? And what are the issues that divide them? Tonight DAVID DIMBLEBY traces the phases of that struggle, pinpoints the personalities who have played decisive roles, and describes the ideas that lie at the heart of the argument.