On September 9, 2019, a test device, which was converted to the same configuration as the TfW Rail units, began with testing in the manufacturing sector, and on April 10, 2020 230006, the first TfW Rail aircraft was tested there. More recently, testing has begun in the field of use. Units are expected to be commissioned at some point in 2020. CAF will manufacture, weld and paint the 197-series fleet at its beasain plant in Spain. The first body of the Driving Motor car had far exceeded this stage until February 12, 2020, when it was represented at the Beasain plant. The laated bodies are then delivered to Newport, South Wales, to assemble/assemble at the new UK CAF plant in Llanwern.  TfW Rail`s current fleet is stored and maintained in the following depots. As of August 25, 2020, 8,769 have been delivered and testing on the Rhymney Line began on March 16, 2020. The first unit commissioned, 769002, finally did so on November 16, 2020.
769003 followed on November 18, 2020 and 769006 on December 4, 2020. The units have removed their pantographs and are only used in diesel mode because they operate on non-electrified lines. The first 769 series was commissioned on November 16, 2020. Due to the very late introduction, the unit was in fact one of the orders of Arriva Trains Wales. Amey Keolis Infrastructure / Seilwaith Amey Keolis Limited (AKI) is the infrastructure manager and will provide asset management services to Core Valley Lines (CVL) on behalf of KAWCL. AKI will provide management and maintenance of CVL`s infrastructure and resources. This work has been delayed for a number of operators wishing to operate the Flex units, including the Great Western Railway and Northern. The scheduled delivery date in May has not been reached and, in July 2019, TfW confirmed that regulatory problems with the units prevented their introduction.  On September 29, 2020, the first DMUs Pacer of TfW Rail`s 142 series (inherited from ATW) was permanently withdrawn from circulation in 142082.
Four of its 142 were withdrawn in October, November and early December 2020. The exemption could have required coupling of MRP-compliant units and further limited the routes on which they can be used (beyond their line authorization and signed pipe depots); However, it was decided not to impose these restrictions, as they could hardly be met in the case of TfW Rail.   It is expected that six 153 trains from the West Midlands will then pass through TfW Rail. On October 22, 2020, two of them had tried to do so, but they failed on the way. Unlike the previous deductible, which was awarded by the Department of Transport, the new deductible was awarded by Transport for Wales on behalf of the Welsh Government.  Nine flex-bi-mode doubles in the 769 series are expected to be delivered by 2019 after the conversion of previously untapped 319 series electric motors to Thameslink, through the installation of diesel generators and additional electronic devices on some previously untapped subs surfaces.  The public body Transport for Wales (commercially separated from the railway company) awarded the Contract for the Wales Franchise and Borders in 2018 to KeolisAmey, which began operating on 14 October 2018.  KeolisAmey uses the ewales and TfW Rail (Welsh: Trafnidiaeth Cymru and TrC Trenau, owned by the Welsh government, for day-to-day operations.