It's hard to think of any institution that more readily represents London than the Underground system. Practical, egalitarian, efficient, popular, logical, organised and yet infuriating, maddening and confusing it stands for everything modern life does in this great world capital. For most of our lives we simply take the Tube for granted, a huge resource that links us to our work, our friends, our entertainment and to every facet of life in the City. The Underground is dependable, ever present - it s that gentle giant that rumbles in the distance, those familiar red circles on the street, and yet it wasn't always like that. But then London wasn't always like it is today.