[17] They are near-identical to the preceding Class 800, the primary difference between the two being the diesel engines originally set to a higher power output and enlarged fuel tanks for their intended use on lengthier unelectrified stretches of railway.

The introduction of Class 802s by Great Western Railway facilitated the replacement of ageing Intercity 125 high-speed trains, and enabled a reduction of journey times.

Both Great Western Railway and TransPennine Express have agreed to participate in trials of battery train technology that, dependent on results, may see fleetwide adoption.

In the event of large-scale electrification being funded and implemented during the train's service life, it is practical for some of the engines to be removed from Class 802 sets if rendered surplus, which would reduce their overall weight by 15% and thus raise operational efficiency.

[21] The purchase of 173 additional vehicles was with the intention that these new bi-mode trains, similar to the Class 800s, would be used on services into Devon and Cornwall.

[19] Initially, because the Hitachi Newton Aycliffe manufacturing facility in County Durham was at capacity, the intention was to build the trains at the Kasado factory in Kudamatsu in Japan.

However, they are furnished with engines that have a higher operating power – 700 kW (940 hp) per engine as opposed to GWR's 800s' original 560 kW (750 hp) (since increased), along with the addition of larger fuel tanks; these enable the Class 802s to better handle the steeper gradients and extended running in diesel mode that has been anticipated on the lengthy non-electrified stretches on which they are typically operated.

[32][33] In April 2022, new sidings in Penzance to better facilitate the operation of GWR's nine-car Class 802 sets to Cornwall were announced.

[6] In March 2016, the train operator First TransPennine Express announced the awarding of a contract to Hitachi Rail Europe and leasing company Angel Trains for the supply of 19 five-car Class 802 sets, which would be primarily operated on the North Transpennine route between Liverpool, Manchester, Leeds, Newcastle and Edinburgh.

[48] The company's management has noted that, in the event of largescale electrification being funded and implemented, the Class 802s could have some of their engines removed to reduce roughly 15% of their weight and thus raise their efficiency.

[18] On 24 May 2024, one Nova 1 unit was converted to a tri-mode train by replacing one of the engines with a battery pack supplied by Turntide Technologies.

[54] This unit participated in the official launch of the Paragon fleet on 25 November, at which the full livery was unveiled at Hull station.

[59] Great Western Railway's Intercity Express Trains are being named after "inspirational people" who have influenced the regions that the company serves.