The British Rail Class 800, branded as the Intercity Express Train (IET) by Great Western Railway (GWR) and Azuma by London North Eastern Railway (LNER) is a type of bi-mode multiple unit train built by Hitachi Rail for GWR and LNER. The type uses electric motors powered from overhead electric wires for traction, but also has diesel generators to enable trains to operate on unelectrified track. It is a part of the Hitachi AT300 product family.

Great Western Railway (GWR) is a British train operating company owned by FirstGroup that operates the Greater Western passenger railway franchise. It manages 197 stations and its trains call at over 270. GWR operates long-distance inter-city services along the Great Western Main Line to and from the West of England and South Wales, inter-city services from London to the West Country via the Reading–Taunton line, and the Night Riviera sleeper service between London and Penzance. It provides outer-suburban services in West London; commuter services from its London terminus at London Paddington to the Thames Valley region, including parts of Berkshire and Buckinghamshire, and Oxfordshire; and regional services throughout the West of England and South Wales to the South coast of England. Great Western Railway provides and maintains the Electrostar Class 387 fleet for Heathrow Express.