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.

Early operations have been troubled by fatigue cracking and corrosion on the aluminium vehicle body shells, particularly on the yaw dampers.

The scheme drew heavily upon the preceding British Rail Class 395 high speed trains produced for Southeastern.

[18][19] In July 2016, it was revealed that GWR's intended fleet of Class 801 units were to be converted from pure EMU to bi-mode due to delays in the electrification.

[1] Furthermore, a high level of flexibility was pursued as to allow the type to be operated on numerous lines with different infrastructure, both in the present and the foreseeable future, such as variable passenger demand and the rollout of electrification.

The front end cars, which feature a collision safety structure compliant with the latest European standards, incorporate an automatic coupling system along with measures to reduce both air resistance and noise.

Train information can be shared between ETCS, TCMS, and the GSM-R wireless communication system to simplify data entry.

Elements external to the GU include the traction converter, fuel tank, automated fire protection system (using high pressure nitrogen gas), and braking.

[25][26] Teething problems surfaced on the inaugural service, the train not only ran late but one of the carriages suffered an air conditioning unit failure that discharged water into the passenger area.

[29][30][31] The launching operator on the East Coast became London North Eastern Railway (LNER) following Virgin Trains' decision to return the franchise to the government; the introduction was postponed by six months on account of the train's electro-magnetic emissions, which had reportedly caused problems with signals and other elements of lineside equipment.

[33] On 14 June 2017, GWR unit 800003 was named Queen Elizabeth II by the monarch herself in a ceremony held at Paddington Station.

[37]Great Western Railway's Class 800 and 802 units are being named after "inspirational people" who have influenced the regions that the company serves.

[40] London North Eastern Railway unveiled a special vinyl on one of their units to celebrate the launch of Azuma to Scotland.

[1] The interiors have reportedly been praised for their increased leg-room and greater number of seats and tables in standard class, in comparison to the trains they replace.

[76][77] The GWR IET has also been criticised for the lack of a buffet car with the catering service instead being provided by a trolley and also the fact that surfboards are no longer allowed on the train due to the limited space available.

[80][81] On 26 April 2021 GWR temporarily withdrew eight 5-car Class 800 sets from service after finding cracks in the yaw damper brackets.

[91][92] On 7 April 2022, the Office of Rail and Road (ORR), which regulates the safety and economics of Great Britain's railway, published a safety report on the fatigue cracks in the aluminium vehicle body shells above the bogies close to the yaw damper bracket and anti-roll bar fixing points.

Further cracks in or near the welds of the lifting plates to the vehicle body were the result of stress corrosion cracking (SCC) in a high-strength 7000 series aluminium alloy caused by a combination of residual stresses from being MIG welded to the body and exposure to air containing sea salt on railway lines near the coast.

[93][94] In 2017, Hornby issued its first OO gauge five-car model of the BR Class 800/0 Hitachi IEP Bi-Mode in GWR Green livery.