In just under 25 years, double-deck buses in the UK have undergone a transformation. Every double-decker in normal service in the UK today is a low-floor bus offering easy access to everyone. This book traces the story of the UK's low-floor double-deckers, from the first tentative steps to the widespread adoption of this layout and the moves from diesel buses to diesel-electric hybrids, to gas, electric and even hydrogen buses built for bus companies of all sizes. It covers the London operators that initially drove the low-floor revolution, along with the major groups, the remaining local authority fleets and a range of enterprising independents that operate them. Where once every double-decker for service in the UK was built in the UK, today many chassis come from mainland Europe and, increasingly, from manufacturers based in other and more distant parts of the world - and UK builders have gained an important foothold in Europe, North America, and the Far East as well. The story is told for the first time, on a model-by-model basis, supported by many unseen colour images, which show the buses in use throughout the UK.