Extract from Railway Gazette June 2021:=
TfW’s fleet of 12 Class 170 DMUs, transferred from Greater Anglia in 2019-20, will now be sub-leased to East Midlands Railway until the end of that operator’s contract in what is expected to be a permanent move. Their release is being made possible by the acquisition of additional Mk IV loco-hauled sets from Arriva’s Grand Central business, changes in the deployment plan for the new CAF Class 197 fleet, and the purchase of eight Class 153 single-car DMUs which are to be refurbished with full TSI PRM accessibility modifications for use on the Swansea – Shrewsbury Heart of Wales line. Meanwhile, the incoming Class 197s will be used on routes in west Wales previously expected to be covered by the Class 170 sets.
All these hopefuls won't be in service by December 2021 but wait and see