Completed in 1841 and covering a distance of around 118 miles, the Great Western Mainline, affectionately known as Brunel's billiards table due to the flat terrain of the route it follows, links the great cities of London and Bristol. This book covers a period of enormous change, starting with the withdrawal of the much-loved HST fleet and the introduction of the Hitachi 800/802 IET fleet. Along with the IET fleet's introduction, the push for electrification of the route has brought about unprecedented changes not only to the route itself but also to multiple units in operation. The DMUs have largely cascaded to the west as EMUs and Class 387s have begun to dominate passenger traffic. Freight and on-track plant also feature alongside unusual visitors and railtours.