Michael Portillo travels from London's Docklands to the Barbican, examining the story of the arrival at Tilbury in 1948 of the Empire Windrush, which brought more than a thousand passengers from the Caribbean to work in Britain. In Limehouse, Michael reflects on the Labour Party's landslide victory at the post-war general election of 1945 and hears what drove new prime minister Clement Attlee to strive for social change.