Who better to join us on our 100th walk than Billy Bragg? He takes Matthew along the route of the Northern Outfall Sewer in East London, which was designed by Joseph Bazalgette as part of his revolutionary waste disposal system for London. Nowadays, thank goodness, it is covered by a Greenway which welcomes walkers and cyclists. Along the way Billy reflects on its history, talks about his own early musical career, sings a new song about a Victorian shipping disaster on the Thames, unleashes his ode to the A13 trunk road and visits the grave of his great grand parents. It is a moving, enlightening and often very funny journey in the company of a legendary musician and campaigner.