The British Rail Main Line Gradient Profiles was originally published by Ian Allan Publishing in 1966. This classic work of reference for railway enthusiasts has been reprinted many times since then but has been out of print for nearly 10 years. The original Ian Allan Publishing book was based on the nationalised BR rail network but this new edition is based on an original book published in 1947 so it is effectively the main line network in the last years of the 'Big Four' on the eve of nationalisation and is organised by the separate four companies plus a separate section on joint railways, rather than by BR Region. This new publication includes details such as troughs that were not included in the previous publication as well as lines that were no longer in operation. It also includes a complete index of all locations shown on the gradient profiles.