The Great Western Railway was the largest British railway company before the industry was re-organised by the government in 1923, with radial routes from London to Penzance and through Birmingham to Birkenhead, and to most places in between. Its first main lines were built by Isambard Kingdom Brunel to the ‘broad gauge’ of 2.14 m (7 ft 0 ½ in), then gradually converted to standard gauge, a process completed in 1892. It maintained its separate identity after the ‘grouping’ of 1923, when it pursued a distinctive policy of locomotive engineering, established by George Jackson Churchward (1857-1933). The principal features of Brunel’s original main line, from Bristol to London, were memorably recorded in their early years by the artist John Cooke Bourne (1814-96).

The principal features of the line, Paddington station, the Hanwell Viaduct in Middlesex, the bridge over the River Thames at Maidenhead, the railway village at Swindon, Box Tunnel, the passage through the City of Bath, and the original station at Temple Meads, Bristol, are the subject of a UNESCO World Heritage Site nomination, under preparation by English Heritage.

A large collection of Great Western locomotives and rolling stock, together with photographs and other documentation, is preserved by the Great Western Society at the Didcot Railway Centre.