They are based on the Class 195 units that were being received by Arriva Rail North at that time, albeit with various customisations to suit the specification and preferences of KeolisAmey and TfW.

They are also expected to replace Class 150 and 153 units on the Conwy Valley line, and to allow extension of services between Liverpool Lime Street and Chester into both north and south Wales.

[13] Orders were placed with a number of manufacturers for new units, including one for 77 new Civity-family DMUs from Spanish firm Construcciones y Auxiliar de Ferrocarriles (CAF).

In January 2020, WalesOnline reported that, based on minutes from Transport for Wales board meetings, the organisation had "raised concerns" that the seats specified by KeolisAmey and CAF for the Class 197 order could be considered uncomfortable by passengers.

TfW argued that these would be "unsuitable for long distance journeys", which could last up to three hours on services operated by Class 197 trains, but noted that it did not have a "strong legal argument" to compel KeolisAmey and CAF to change the specification.

[21] On 18 January 2022, the Office of Rail and Road (ORR) granted authorisation for 20 two-car and 12 three-car Class 197 sets to enter passenger use; these initial units were not equipped to use the European Train Control System (ETCS).

In November 2023, the 197s started working between Wrexham and Bidston on the North Wales/North-West England Borderlands line, alongside the 230s, though this is only temporary until the 230s' reliability issues are resolved.

[26] In June 2024, the 197s started full service in and out of Pembrokeshire - between Carmarthen and Milford Haven, Fishguard Harbour, Pembroke Dock and Tenby every day.

[4] TfW organised the Magnificent Train Journey competition, aimed at primary school children, to name its Class 197 units.