It ran local services from Paddington to Slough, Henley-on-Thames, Reading, Didcot Parkway, Oxford, Newbury, Bedwyn, Worcester Shrub Hill, Hereford, Banbury and Stratford-upon-Avon.

It stated that, in the light of the £1 billion plan to electrify the Great Western route from London via Bristol to Cardiff, it wished to try to negotiate a longer-term deal.

[46] Canadian-born comedian Tanyalee Davis, who has a form of dwarfism, said she was humiliated when a Great Western Railway conductor made an announcement that she was "causing problems" which had delayed the train.

[48] In 2015, the imminent arrival of the new Class 800 trains provoked a series of strikes by the RMT union over who has the right to control the doors.

[54] In April 2021, cracks were discovered in the yaw damper brackets (part of the suspension system) of Class 800 and 802 InterCity Express Trains (IET).

Cracks had now been found in the lifting pads (a component fixed near the bogie) and it was feared that if these were to fall off they may cause injury or derailment.

[59][60] A further six Class 387 units were loaned from Govia Thameslink Railway in July 2021 and used in a common pool with GWR's existing 387/1 fleet, being surplus to requirements while the Gatwick Express service was suspended.

The fleet of 57 Class 800 trains from the Hitachi A-train family is used to operate most of GWR's long-distance services between London and destinations such as Swindon, Chippenham, Bath Spa, Bristol Temple Meads, Newport, Cardiff Central, Swansea, Carmarthen, Cheltenham Spa, Oxford, Worcester Shrub Hill and Hereford.

[62] Long-distance services between London and destinations in the west of the GWR network (such as Paignton, Newquay, Plymouth and Penzance) are mostly operated using the fleet of 36 Class 802 trains, the first of which was introduced on 20 August 2018.

[64] Hitachi planned to test a tri-mode Class 802 in 2022 fitted with batteries in an attempt to reduce emissions when entering and leaving stations.

[68] The Class 165 "Networker Turbo" is a two- or three-coach DMU used on shorter-distance services in the Thames Valley area, with the majority based at Reading Traction Maintenance Depot.

The Class 387 "Electrostar" is a four-coach EMU built by Bombardier, with a 2+2 seating layout, tables, power sockets and free Wi-Fi.

Bombardier Transportation at Ilford Depot had modified twelve of these trains by December 2020, installing new first-class seating, Wi-Fi, luggage racks and on-board entertainment, to be used on Heathrow Express services.

[74] Great Western Railway retained 24 power cars and 48 carriages from its former High Speed Train fleet to form 12 'Castle' 2+4 sets.

The sets are progressively being fitted with automatic doors and controlled emission toilets, to allow their operation beyond 2020, at Doncaster Works.

Until 2017, GWR operated the vast majority of its long-distance services with a fleet of 58 InterCity 125 High Speed Train sets,[77] each consisting of eight Mark 3 coaches sandwiched between two Class 43 locomotives.

GWR operated the largest InterCity 125 fleet, owning five sets outright; the rest were leased from Angel Trains and Porterbrook.

The MTU engine proved the better option, both for reliability and for emissions, resulting in FGW, Brush and Angel Trains starting the HST Modernisation programme.

The fleet of 17 two-coach Class 150 Sprinter units was inherited from Wessex Trains as part of the Greater Western franchise shuffle.

The fleet is widespread throughout the former Wessex area, and carried a maroon livery with advertising vinyls for South West Tourism.

At the same time, the exteriors of the vehicles were repainted in the updated FGW livery, including artwork depicting various local places of interest.

The timetable change in December 2019 saw the start of the 158s taking over from the 143s primarily on the Tarka Line to Barnstaple, with some of the units also working on the Cardiff / Bristol to Penzance route alongside the Castle sets.

These were sub-leased from Northern Rail (where they had been stored), in part to cover for refurbishment of FGW's Sprinter fleets but also to allow the Class 158s to be re-formed as three-coach sets.

[108][109] The 150/1s in the GWR fleet transferred to Arriva Rail North in stages, beginning with the first three in August 2017 when their leases expired,[110] and ending in April 2018.

[112] In February 2023, GWR purchased a number of assets from the administrators of battery train manufacturer Vivarail, including 67 former London Underground D78 Stock carriages and intellectual property rights to the Class 230.

Although initially planned for use in London and the Thames Valley, while 12 Class 387 units were modified for Heathrow Express services, the future plan for these units was to be operating on services between Oxford, Reading and Gatwick Airport, which would have meant operating on non-electrified lines, 25 kV AC OHLE and 750 V DC third-rail routes.

In December 2022, GWR announced that the introduction of the Class 769 fleet would be abandoned and the units handed back to Porterbrook in April 2023.

The HST fleet was repainted to match as they went through overhaul; however, the livery on the power cars was progressively altered to a plain blue base with pink and gold stripes, following problems with dirt build-up on the large white areas.

[126] The rebranding of the company as Great Western Railway introduced a new GWR logo and a dark green livery with white stripes and grey doors in September 2015.

Channel 5 broadcast two television series looking into day-to-day challenges of the Great Western mainline, including events at Dawlish (as well as the sea wall destruction), Cheltenham race day and rugby at Cardiff.